We currently have radiant heat. We must change over to electric wall heaters. My question spans the installation of the new heaters and if it is possible to use the existing wiring without rewiring and tearing into the sheetrock. I have outlined what we want to do.

Any input as to if this is feasible or not would be appreciated. And thanks in advance for any response.
Pierce.

What I would like to do:

1. I want to use the King Deca model 2022 wall heater.
http://www.king-electric.com/prodtemp.asp?prodID=DEC

2. I want to put the Deca heater into the existing space where the current blower/heat source is now.

3. I will remove the current blower and other pipes in the wall; this will leave the metal box in place with the electrical wire. I want to install the new metal box within the existing box, mounted towards the top of the existing box to allow for the blower vents in the current wall panel grill to match up with the new heater blower outlet. I believe the new box will fit directly inside the old box without much problem. I want to use the existing wall panel grill to fit over the new blower unit.

4. My understanding is that the electrical wire that runs through the wall to all 4-heater blowers (currently in place) is 12/2 wire. It is my understanding that the new heater units are 208v, as such, they are capable of running off 12/2 wire (as opposed to 14/2 wire).

5. There is one circuit breaker for the 4 existing blowers in the panel. The Circuit breaker is 15 AMPS. The new heater and blower draw 9.4AMPS each. I want to replace the existing circuit breaker with a new 40AMP breaker.

NOTES:
The current panel has a total 325AMPs in circuit breakers installed. With the new breaker the total AMPS will be 350AMPS. (the panel is currently broken into 105 and 220 per side. With the new amp upgrade it will stand at 130 and 220)

NOTES:
The unit’s AMP service draw from outside is 100AMPS.

NOTES:
Each of the new Deca 2022 Wall heaters have the following specifications:
Ø 208Volts
Ø 9.4AMPS
Ø The heating element assembly provides 7 possible wattage configurations:
500, 750, 1000, 1250, 1500, 1750, 2250

NOTES:
My understanding of a 12/2 wire allows it to load up to a total of 3,328 watts (16x208)

6. I want to use the existing wire in the wall to wire/hook up the new heater units. I do not wish to run additional wire, nor do I wish to add a second circuit breaker and divide the 4 wall units into two separate wire runs from the panel.

7. With a total single wire line wattage draw at 3,328 watts I want to configure the four new wall heaters as follows:
Living room – 2 at 500 watts each
Lower Bedrm – 1 at 500 watts
Upper Bedrm – 1 at 1750 watts

This makes for a total combined wattage on the one wire at 3250 watts. This configuration is based on the wire capability of 3328; if the wire capacity is more, than I would change (ideally) the above configurations as follows:

Living room – 2 at 1750 watts
Lower Bedrm – 1 at 1000 watts
Upper Bedrm – 1 at 2250 watts

This 2nd configuration makes for a total combined wattage on the one wire at 6550 watts.

8. I want to use all of the existing thermostats that are currently in place.

9. I want to install a wireless thermostat connected to the gas fireplace. I want to “mount” the wireless thermostat next to the existing living room thermostat, which is located in the hall. (this will be used as supplemental heat to boost the efficiency of the 2 electric heaters in the living room)

Can I do what I have outlined above?
What is the maximum I can configure the individual wall heaters to. (as noted above)?
Is the upgrade to the 40amp circuit breaker enough or does it need to be more?
Can I run all 4 heaters on the single wire run?
Is there something I am missing??

I think you need to rethink the project. You must stick to 20 amp breakers with #12 wire. I question if you have enough available incoming service to support electric resistance heat. The electric company may not upgrade you if you ask. I will leave the details to tkrussel thinking he has a much better understanding of current codes.

If you have natural gas available, I am not sure it makes good sense to switch to resistance heating with ever climbing prices. Yes gas is going up this year, but electricity will continue to climb too. If you have walls full of old leaking hot water pipes, you may not have any cheap, simple options. New pipes, or a forced air system would mean extensive ripping up sheet rock.

Thanks for your reply.
Unfortunately our only option is to install electric wall heaters. I would rather replace the defective tubing for the radiant heat as I like that much better, however the cost for doing so with the drywall repair is over 15K. (Thanks Dupont!)

I have been told that there is enough power coming to the unit (this is a condo). The option we were given based on 14/2 wire was to run new (220) wire to the four new heaters and break it up between two breakers. (My unit has 12/2 wire however)

Another option was to leave the 14/2 wire and run 110 heaters on two of the new heater units (due to gas fireplace in proximity to the first to heater units) , and only run new 220 wire to the other two units allowing for greater wattage.

My dilemma is that I want to use the existing 12/2 wire, upgrade the circuit breaker and adjust the individual heaters accordingly so to balance the total wattage draw among the four new heaters (as outlined above). I do not want to cut and replace sheet rock.

Are the heaters available for 220-240 volts? If the new heaters don't have any 120 volt components, you could install a 20 amp double pole breaker and use the existing 12-2 wiring for it. That would allow you about 4000 watts. Do you think that much heat will be enough? How big is the area, and how severe is your climate?

That $15K sounds high. I would try to get another estimate before I gave up on the radiant heat.

First off, I need to confirm that you truly have 208 volt. It is possble, because you may be in a condo that is part of a larger building that has 120/208 volt 3 phase utility power. You did chose the 208 volt model, which,if there is 208 volt, is correct. I will have to trust you on this, but implore you to confirm the voltage you have, either 208 or 240 volt, and order the properly rated units.

You must confirm the cable is #12 copper wire.

You cannot, under this circumstance, connect #12 wire to a 40 Amp breaker.

20 Amp breaker connected to the existing #12 wire is the maximum,and at 208 volt, you are correct the maximum allowable wattage is 3328.

The heat unit is field convertible for seven wattage settings. You state the unit amps is draws 9.4 amps.Where does that rating come from? It is not in the manufacturers spec sheet.

Each wattage setting will draw it's respective amperage, using the power formula P=EI.
500 watts = 2.4 amps
750 watts = 3.6 amps
1000 watts = 4.8 amps
1250 watts = 6.0 amps
1500 watts = 7.2 amps
1750 watts = 8.4 amps
2250 watts = 10.8 amps

So where does the 9.4 amps come from? Each heater set at a different wattage setting will draw different amps.

You can configure the heaters any way possible that will not exceed the 16 amps draw or the 3328 watts.

The existing thermostats can be used only if they are rated to handle 208 volt. You must use a double pole thermostat to control the new heat units.

The addition of the ratings of circuit breaker handles is completely irrelevant. This means absolutely nothing. The important value is the rating of the feeder which feeds the panel, you state 100 amps. To be sure you have enough capacity with 100 amps, I need to get a great more detail to be able to perform load calculations.

There is something I am not completely understanding, how many 2 pole 15 amp breakers connected to #12 wire is there? I re-read your post and once get there are two, and later I get there is one. In the beginning I took it as four heaters with four breakers, I am unclear about this.

To summarize, each existing circuit can only handle the 3328 amps at 208 volt on #12 wire connected to a 2 pole 20 amp breaker. AND DO NOT USE A LARGER BREAKER THAN 20 AMP ON #12 WIRE.

The wireless tstat for the gas heater is fine, providing it is not a millivolt gas valve unit.

I sure hope this helps. I still get the feeling I am missing something in your explanation, just can't put my finger on it.

Hi, and thank you very much for your help/input!

This unit is part of an 18 unit building. I went outside and checked the box where the meter is. There are 4 supporting meters on my box. On it, it says:
AMPS: 800, Phase: 30 Volts: 208Y/ 120 with Cat No: m3m412r-ab-7b

The larger box that appears to feed the smaller boxes says 600AMPS 240 VAC Max Phase: 3PH (this is to be upgraded to be able to support all 18 units for the elect heat)

Based on this and what I have been told I am 99% sure that we have 208V

I confirm that it is 12/2 wire.

I called the dealer for the heaters and asked him what the max amp draw for both the heater and the fan was. He told me that per the manufacture it was 9.4AMP max draw. I did not know any different as has been pointed out in the last post from tkrussell with regards to different heater watts pulling different AMPs.

I understand from you NOT to use a 40AMP Breaker. Question is (as reference from the above Labman post) could you use a 20amp double breaker, which as he notes would allow up to 4000watts as opposed to 3328watts on a single 20amp??

With my original watt configuration, and based on tkrussell new numbers of watts and AMPS, my 1st configuration would equate to a total 15.6 Amps, that sounds as if it would be OK for a single 20 amp breaker and the 4 heaters configured as follows:
500/500/500/1750 = 3250watts.

My new question is if one could use a 20amp double breaker to increase the wattage to 4000, then I would reconfigure the heaters as follows:
750/750/750/1750 = 4000watts
This would make the total AMPs based on Tkrussels calculations to 19.2AMPS. Is this OK?

I have model 859M room thermostat (total 3, 1 for lv room 1 ea for the bedrooms). I do not know for sure if they are rated for 208V.

CURRENTLY: there are 4 fans on 1 wire, all controlled by one 15-amp breaker.
I want to replace the 4 “radiant heat fans/units”. These four fans draw 1.5amps each. I want to use the existing wire, put in the proper breaker (single 20amp or 20amp double breaker) and configure the wattage on the 4 heaters accordingly.

The inside of my boxes looks like this:
Left
15 heat – this is the one I want to replace
15 dishwasher
15 disposal
15 fam lts
15 kit lts
15/15 mst bed/ dn bed

Right
40
40 range
30
30 dryer
20
20 appliance
20/20 micro/ dn bath gfi

OK bear with me I am going to respond to each question or comment as I read this.

Yes you do have 120/208 single phase in your unit. The building has three phase and each unit has single phase, this is very common with large dwelling buildings.

Youcan only load a 2 pole 20 amp 208 volt circuit the 3328 watts, or 16 amps on each circuit.. As I stated you will need to use all 2 pole breakers to feed 208 volt rated heat units. A single pole will only give 120 volt circuit. I am not sure but seems that there is a misunderstanding, no single pole circuits can be used for this heat. Please get back to me if there is anything you do not understand about this.

Labman must have used 240 volt in his calculation to arrive at the 4000 watts or 16 amps.The power calc must use 208 to arrive at the proper max watts allowed.

You can connect three 500 watt units and one 1750 watt unit, totaling 3250 watts that will draw the 15.6 amps. And this circuit will need a two pole 20 amp breaker on #12 wire to deliver 208 volt to all the units.

The wrinkle is the thermostat wiring, eachstat must be 208 volt rated, if not they can be changed,however, two wires must feed to the stat, and two wires must run from each stat to it's respective heater. The tstat must be a double pole, one pole is a make and break switch and the other pole is control by the temperature sensor.

Great job on the house load info, however I need just a bit more.

Can you give the following info:
Brand name or manufacturer of the thermostat
How many wires are at each tstat
Size of main breaker, I recall 100 amps,but lets confirm.
Total square footage area of all living space only, do not add any basement or unfinished attic or crawl spaces. Include bathrooms laundry, hallways stairways, etc. Everything that is finished space.

The single pole 15 amp breaker that you want to change will need to be a 2 pole 20. Are there any spares or spaces? You will need one more pole space to turn the single pole into a double pole/ Or you may need to convert two other single pole breakers into half size or tandem breakers to free up a pole for the added one from the 2 pole. I see that there are already two tandem breakers being used.

Get back with the missing info and any other questions and we should be able to wrap this all up

A clarification. I was assuming a typical single residence with 2 opposite 120 volt feeders. Thus you could have 240 volts and 4000 watts with a 12-2. With the 208 volts, you are limited to the 3328 watts as TKrussel says.

For that many units, the $15K may be reasonable.

Thank you very much once again for your help.

I took pictures of the inside of the box and behind the thermostat.

The three thermostats are a “King” 859M room thermostat. On the back of it where the wires come out there is another number stamped on it as noted below:
The Stat in the lv room to the 2 heaters has black, red and copper (9811)
The Stat in the dn bd has black, red, small white and a copper wire coming out of it. (9508) (see pic)
The Stat in the mstr bd has black, red and copper (9811)

I am told that the size of the main breaker is 100amps. There is no main breaker shut off on the panel or inside the box.

There are no more spaces or any spares on the panel or inside the box.

NOTE:
Before I go over sq footage, when I took off the panel again, I saw that there were two black wires coming from the wall and tied together before entering the breaker. I disconnected these and hooked them up separately. I found that one of the wires goes to work the blower in the up stairs mstr bedroom only. The other one goes to work the other three blowers 2 in the lv room, and one in the dn stair bedroom). (See below for my query on this)

SQ Footage:
The upstairs bedroom, bath and week in closet measure 397sq feet. All three rooms have high vaulted ceilings. Based on the bedroom and bath only I calculate the watt/sq foot at 1965w @6 2483w @ 7.5
The dn stairs bedroom measures 120sq feet. 720w @ 6 and 900w @ 7.5
The lv room, kitchen hall and bath combined measures about 588sq feet (this area is also heated by a gas fireplace). 3328w @6 and 4043w @ 7.5.

I am not including anything for the U shaped stair well (54sq ft) up to the master bedroom or 2 closets on the main floor.

Based on my original one wire scenario, I configured the heat as follows:
Mstr – 1750 8.4amp
Bed 1 – 500 2.4amp
Lv rm – 500 x 2 = 4.8amp
I am aware that based on the sq footage to watt calculation I will be “under” the preferred amount.

Now that I see there are two separate wires as I note above, I would look to contemplate configuring the system as follows pending there is enough “room” to reconfigure the other breakers in the panel for the necessary 2pole 20 as noted by Tkrussel. (? )

Mstr – 2250w (on separate circuit) 10.8Amps

Bed 1 – 750w 3.6amps
Lv room – 1250w x 2 = 12amps
Total 15.6amps, 3250watts
Or
Bed 1 - 1000w 4.8amps
Lv room – 1250w x 2 = 12amps
Total 16.8amps, 3500watts
Or
Bed 1 – 500w 2.4amps
Lv room – 1500w x 2 = 14.4amps
Total 16.8amps, 3500watts

BREAKERS:
(original configuration) Based on what Tkrussel is saying, and I am understanding (?) you will need two slots in the panel to put 1 fat/wide aka 2pole 20amp breaker for the original configuration. And that is because this is 208V heat units. AND if we only use a single pole 20AMP with this heater it will deliver only 120Volt heat which will make the heater not work correctly??

(question) IF I wanted to use only a single pole 20AMP breaker than I would need to order a different heater: i.e. the DEC 1215 to configure this at 120Volt.? – just a question. IF this was the case then all of the room wattage configurations would remain the same 500/500/500 except the mstr bedroom would go to 1500W, as that is the highest allowed for this model heater.?

(Possible new configuration based on 2 wires coming into panel)
Master bed on a 15amp 2 pole breaker?? 2250W 10.8AMPS 208V DEC2022
(Question: we cannot use a single pole 15 amp in this case? correct? )

Bd/Lv room on a 20amp 2 pole breaker. Total 15.6amps, 3250watts, 208V DEC2022
??Could you allow the bum up to Total 16.8amps, 3500watts??

OR
Master bed on single pole 10amp breaker, 1500watts 7.2amps 120V DEC1215
Bd/Lv room on a 20amp 2 pole breaker. Total 15.6amps, 3250watts, 208V DEC2022 (or total 16.8amps if allowable)

I don’t know if there will be enough space in the box for 2 2pole breakers. Currently:
15 blowers
15 diswasher
15 disposal
15 fam lts
15 kit lts
15/15 mst bed/dn bed lts

reconfigure as (origional plan)
20 heat 208V 500/500x2/1750w
x (include with above)
15/15 dish/disposal
15 fam lts
15 kit lts
15/15 mst bed/dn bed lts

or with 2 wires one for master and one for dn stairs:
20 heat 208V lvroom/bed 1250x2/750w
x (incl with above)
15 heat 120V mstr bed ----- or?? 1500w
15/15 dish/disposal
15/15 fam lts/ kit lts
15/15 mst bed/dn bed lts

if we put the DEC 1215 heater at 1500 watts 120V on its own circuit, in the mstr bedroom, how much difference in efficiency and heat out put would there be to that of our original configuration of using 500/500x2/1750 208V heat?

honestly I don't understand what the difference between having the 120v heaters and the 208 heaters are. If they can be configured at the same wattage settings, but just using different sized breakers single 20 and double 20

I just got this late at night and I will need some time to go through and check everything out.

But first, after my last post something occurred to me. I need to ask, are you planning to perform this work yourself?

In the New England states I am licensed in, only people that live, and own their single family home can perform their own electrical work. Before I continue, you must confirm that you can perform work in a multi-family dwelling in your state or city.

If you make the slightest mistake, be aware that you, and only you, personally will be responsibe for the health and welfare of all the other innocent occupants residing in the builidng, along with the structure itself.

Any death caused by your negligent actions can be considered criminal and you can be charged with, hopefully, a minimum charge of involuntary manslaughter. I am not an attorney, so by all means, please consult with one, along with your insurance agent.Your insurance carrier will likely leave you by the side of the road.

I strongly recommend you consider this, and be absolutely sure how you will proceed. Before I continue, I will need to know the state so that I can confirm the local laws. I will not be an accessory to a felony.

As an example, I convey to you the exact allowable amount of wattage that can be connected to a 20 amp 208 volt circuit, 16 amps or 3328 watts, and you still ask if you can go to 16.8 amps.

16 amps means 16 amps, not 16.8. What other short cut will you take?

This is not a game, this stuff will kill people and burn buildings down!

Thanks for your concerns and reply.

Firstly, we live in Washington State. I am gathering information mainly due to 3 different electrical contractors telling us three different stories. For example: One says we have 14/2 wire and another does not. After pulling all of the blower panels off we confirmed via the stamped reading on the sheathing that it is 12/2 not 14/2. Another example is one contractor saying we cannot hook up any wall heaters (based on what we have been speaking about), and another saying we can.

I guess what I have been trying to ascertain is an unbiased ($$) opinion from someone who understands what it is we want to accomplish. And because I am one of the couple of people on the property that can follow what we have been conversing about, puts me in the forefront. All of what we are speaking about is being discussed with the other homeowners, and from this point we will go back to a contractor and tell them what we want to do as opposed to them telling u$ (ignorantly) what to do. At the end of the day all of this will be signed off by an inspector as needed, because nobody wants to make any mistakes!

Our building was engineered by an East coast Architect. The construction on it is exceptional, especially when concerned with the insulation and soundproofing. The only problem was the subcontractors who put in the radiant heating system, although this mainly had to due with Dupont’s subsidiary corporation delivering defective tubing. This last winter most units did not have the radiant system hooked up. Due to the insulation, many if not most units did not need much heat even though we experienced temps in the 20s. The gas fireplace alone was enough to heat the entire unit. This is partially why the "OK" for the smaller wattage configurations based on the total sq footage.

Some homeowners are not even going to change their heating system out and just use their gas fireplace. A few others may shell out the 15k -18K to keep the radiant heat. I for one like the radiant heat better however I don’t have an extra 18k to put into it and believe this solution will work out just fine in conjunction with the gas fireplace.

With regards to the comment about “short cuts”. Indeed the comment is justified, as this is NOT a joking matter, however my post was only a question, and not a means by which to circumvent a situation. If you say that 16amp is the max on a 20amp circuit, I got it; I did not know if it was at all possible, that's all.

Thanks again for your time and input on this matter, it has indeed helped us substantially!

I am so glad, you have explained thouroughly your situation, which is perfectly feasible, and I commend you for your initiative. Now I understand completely, and am confident that you understand my position .

I can continue with a clear conscience. It is now early morning, and I need to get to work, however will have plenty of time to analyze and comment on the details later this afternoon.

I can understand your confusion, dealing with various contractors, and the different answers they provide. Having been a VP on a condo board, I also have experience dealing with the owners, also.

I will provide the best answer I can, however, you and the board may want to consider hiring an engineer, to sift through the various solutions, and design a heating system that will suit all units the best, individually and collectively.You may want to check with your local building official to learn if there is a state statute, based on the occupancy and size of the building, that may require an engineer to design this electrical system.

You will then have someone knowledgeable of the electric codes, and be able to have a objective benchmark regarding the actual installation. Relying on a contractor to deisgn and layout a system such as this should be not a problem, however, you need to depend on his knowledge. As you can see, not all contractors are equal in their capabilities.

If an engineer costs $2000.00, the costs can be shared by the unit owners. I will get back to you with my calcs and recommendations, however,please consider my thoughts.

The square footage I ask for is to perform an electric load analysis to determine if your panel can safely handle the added load. Additional calcs will need to be performed on the entire building's collective load to be sure building's service can handle the potential load from all the units heat.

Be back to you asap.

First off , sorry to be so blunt, I am very passionate about this business, and never know who is trying to get away with what.And since many people view this forum, I hope to get a point across.

Seems that King no longer lists the 859M stat, but the image shows me it is a single pole stat. A 2 pole (double pole) stat will be needed to control a 208 volt heat circuit, along with two 2 wire cbles in the stat, one in as a feed, and one out to each heater. This looks OK from the image.

The main breaker will be found out at the meters, find your meter and the main is alongside of it. A main breaker is not required at the panel.

The separate cable to mst bdrm is good news, means you can run a larger heater for the room, without adding to the other circuit, and leaves room for more heat on that other.

I am not going to speculate what the heat watts per SF is for WA state, here in New England we use 9 W/SF for new construction using 6 in walls, and 11W/SF for 4 in walls, both insulated properly, and more if the building is not insualted to current standards.

I need the SF to do the load calcs to determine if 100 amps can handle the added load.

Based on approx 1200SF of useable space,and the min amount of load allowed by the code calcs, the total calculated load is 76.18 amps. You can only load a 100 amp service 80%, or 80 amps max.

The 100 amp service to your and each of the other units, assuming the SF is similar, cannot handle the additional load of the proposed electric heat. I realize this is not what you want to hear, but based on the info provided, I am unable to tell you otherwise. If you like you can find an edition of the 2002 National Electric Code and refer to pg 1144 Examples, which show how to calculate the various occupancies, and refer to Article 220 for the details.

I need to implore you to hire an engineer to perform these calcs, and determine how you can proceed. Are the original plans of the building available? Perhaps a copy can be found at your local building/code enforcement office. These would help an engineer expedite the calcs, by being able to see how the original load calcs were performed, even you can review these and see how the unit service was arrived at.

Hiring a contractor to do what ever work you may decide without performing due diligence to confirm the added heat load can be serviced may prove to cause more problems than you have already.

Perhaps you can ask for help and advice from the local inspector. Another thought would be to check with a local tech school, for advice, perform the calcs, and even do the work if something can be done.

Please take a moment and get back to let us know how you proceed and what you do discover.

I asked the very same question concerning load.

I was told that the main power (for 18 units) next to the meters would need to be upgraded. As I may have mentioned before it is currently:
600AMPS 240 Max 3PH, with 3 A3T500 Fuses inside the box. I am not aware to how much more they well going to bump it up to.

When I asked about the unit. They said we had 100amp Service (as previously stated). By the meter, where the main breaker switch for the unit is located; it has a 2pole 100/100 breaker. One reads:
Type TB
120/240 VAC
Cu/A1
2pole SR101
E162469
LR 102619

And the other reads:
Common trip.

The one electrician we had consult and to whom a few are looking at using on this matter was going to use the same heaters however rewire everything because he said it was 14/2 wire. (it is not) In addition with regards to the main he stated:
""Upgrade electrical services to full ampere ratings at 120/208 volts, 3 phase as necessary""
And with regards to the unit he stated:
""Add 4 fan forced electric heaters totaling up to 6750 watts maximum.""

That is his plan.

He was rewiring so that it was 220, and when I asked him if there was enough power servicing the unit he said there was. When I asked him about upgrading the power outside he said that had to be done, ""however that we could go forward in changing the units and that there was enough power outside to operate the new heaters now"", ""yet it needed to be upgraded anyway to satisfy X."" (upon execution we were told that it will take 6 to 8 weeks to upgrade the main, however work could commence on the 18 units immediately.)

The units electrial box currently has a total 325AMPs in circuit breakers installed

At the end of day, based on what I have Learned from you herewith, I will look to have another electrician come out again. At least this time around I shall be a little more informed.

Indeed it is disappointing to hear there is not enough power to the unit to run the new heaters. i was actually "getting it". Thank you.

I understand that it is not good news that the unit service is not adequate, however, how you came to question the advice you were given is a blessing in disguise. You should consider yourself very lucky to have been so inquisitive, for yourself, and the safety of the otherunit owners.

I notice you do not mention, either agree or disagree with hiring an engineer to help with the designing this heating system and the apparent service upgrade. I recommend that you check with your local building/electrical official to deterimine if this may be required to obtain approval for permit application. Though you may get around this, even if technically required by state statue, the inspector may not ask for load calcs upon completion of the job, and something is done improperly due to the wrong or lack of calculations, the only one to suffer will be the unit owners. Sure you will be able to sue the negligent contractor, but I guarantee that you will need to live through the winter before any judgement or settlement will be arrived at.

The contractor you have been dealing with needs to be avoided. His statement to rewire the unit service to "220 volt" is an illustration of his ignorance. The main service is 120/208 volt 3 phase, he cannot get 220 volt from there, 208 is all that can be gotten at the unit panel. Just the statement "220 volt" is odd, since 220 volt is not a standard voltage in the USA, only 208, 240, 277, & 480 volt. If he is considering replacing the 120/208 v 3 ph main service with a 120/240 single phase service also shows a lack of understanding, even thou it may be possible, it is not reasonable or practical.

If he has stated the unit service can handle the added load without doing the calcs shows his laziness, and appears to be making assumptions. This can be dangerous.His observation of #14 wire that is actually #12 also shows his lack of basic knowledge.

The units can be upgraded now, somehow, not sure exactly how, but if the main service is not capable to handle the added load, then the main needs to be upgraded before the heat can operate. If he was planning to upgrade each unit to 3 phase 100 amps, that is a good solution to add more capacity to each unit. I hope that is exactly my understanding.

The addition of the ratings of each breaker in a panel is totalling irrelevant information. This means absolutely nothing, if any electrician refers to this in anyway, run, do not walk away run away from him.

The total heat load of 6740 watts per unit for 18 units, connected at a 120/208 v 3 ph service must be calculated at 100 % and will add 337 amps to the main service. This means, at face value, the main service needs to be upgraded to a possible 1200 amp main, maybe at least a 1000 amp main. Without having all the details of each unit, and the common areas, I am unable to perform reasonable and accurate result.

Who is planning to upgrade the main service? Why do you not know by how much?

If you go to another contractor, how can you be sure he is correct? How can I convince you to seek the advice of an engineer? This is a complicated issue, not necessarily without a reasonable solution. However, there may only be one or two possible practical solutions, which need to be explored for obvious economics and safety issues.

As I mentioned before, the original plans are available somewhere,from the original design firm or the city plan office, and will prove to be very helpful to plan the impending upgrade.

You can find an electrical contractor that specializes in "design/build" projects.This contractor will either have an engineer on staff, or subcontract one, to produce a design that is practical and properly documented. You may need to look towards a larger contractor that has a reputation working on large projects.

I do recognize that you certainly have your hands full, I do get that you are now a bit more knowledgeable, but I am not sure you have enough to be able to sort through the requirements and calculations. I do hope you can get through this as inexpensively as possible, and end up with a properly rated system that will operate safely for years to come. Please keep me posted. I would like to see how you proceed and what the ultimate solution and related costs are.

You may email me directly at [email protected] if you like. Please keep in touch. If you like, I can, believe it or not, recommend a qualified contractor in Washington State, or almost any state, including Canada, and other areas, even thou I am in New England, email me for the details and I can explain how.

Quote:

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Originally Posted by pierceB

We currently have radiant heat. We must change over to electric wall heaters. My question spans the installation of the new heaters and if it is possible to use the existing wiring without rewiring and tearing into the sheetrock. I have outlined what we want to do.

Any input as to if this is feasible or not would be appreciated. And thanks in advance for any response.
Pierce.

What I would like to do:

1. I want to use the King Deca model 2022 wall heater.
http://www.king-electric.com/prodtemp.asp?prodID=DEC

2. I want to put the Deca heater into the existing space where the current blower/heat source is now.

3. I will remove the current blower and other pipes in the wall; this will leave the metal box in place with the electrical wire. I want to install the new metal box within the existing box, mounted towards the top of the existing box to allow for the blower vents in the current wall panel grill to match up with the new heater blower outlet. I believe the new box will fit directly inside the old box without much problem. I want to use the existing wall panel grill to fit over the new blower unit.

4. My understanding is that the electrical wire that runs through the wall to all 4-heater blowers (currently in place) is 12/2 wire. It is my understanding that the new heater units are 208v, as such, they are capable of running off of 12/2 wire (as opposed to 14/2 wire).

5. There is one circuit breaker for the 4 existing blowers in the panel. The Circuit breaker is 15 AMPS. The new heater and blower draw 9.4AMPS each. I want to replace the existing circuit breaker with a new 40AMP breaker.

NOTES:
The current panel has a total 325AMPs in circuit breakers installed. With the new breaker the total AMPS will be 350AMPS. (the panel is currently broken into 105 and 220 per side. With the new amp upgrade it will stand at 130 and 220)

NOTES:
The unit’s AMP service draw from outside is 100AMPS.

NOTES:
Each of the new Deca 2022 Wall heaters have the following specifications:
Ø 208Volts
Ø 9.4AMPS
Ø The heating element assembly provides 7 possible wattage configurations:
500, 750, 1000, 1250, 1500, 1750, 2250

NOTES:
My understanding of a 12/2 wire allows it to load up to a total of 3,328 watts (16x208)

6. I want to use the existing wire in the wall to wire/hook up the new heater units. I do not wish to run additional wire, nor do I wish to add a second circuit breaker and divide the 4 wall units into two separate wire runs from the panel.

7. With a total single wire line wattage draw at 3,328 watts I want to configure the four new wall heaters as follows:
Living room – 2 at 500 watts each
Lower Bedrm – 1 at 500 watts
Upper Bedrm – 1 at 1750 watts

This makes for a total combined wattage on the one wire at 3250 watts. This configuration is based on the wire capability of 3328; if the wire capacity is more, than I would change (ideally) the above configurations as follows:

Living room – 2 at 1750 watts
Lower Bedrm – 1 at 1000 watts
Upper Bedrm – 1 at 2250 watts

This 2nd configuration makes for a total combined wattage on the one wire at 6550 watts.

8. I want to use all of the existing thermostats that are currently in place.

9. I want to install a wireless thermostat connected to the gas fireplace. I want to “mount” the wireless thermostat next to the existing living room thermostat, which is located in the hall. (this will be used as supplemental heat to boost the efficiency of the 2 electric heaters in the living room)

Can I do what I have outlined above?
What is the maximum I can configure the individual wall heaters to. (as noted above) ??
Is the upgrade to the 40amp circuit breaker enough or does it need to be more?
Can I run all 4 heaters on the single wire run?
Is there something I am missing?????

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if you already have an existing central air system.. it much cheaper ( installation/ operation) to convert to a forceair hot water system ** 1kw= 3450BTU/ 1 therm(cubic FT ) of gas give off at least 80000BTU

Hi,

I've new wall heater (Williams 5009622) for a cabin in South Lake Tahoe, Ca to heat an area of 1000sqft. I've following 3 questions related to the wall heater:

1. How much difference does a wall heater blower make in terms of comfort
And efficiency?

2. The estimated cost for having a blower installed by a local heating
Contractor is about $363 ($225/hr for labor + $138 for parts). I could buy
The same wall heater new for $631 online. Is it still a good investment to
Have the blower installed?

3. Is the installation for the heater blower a difficult job? Would the installation be manageable for an inexperienced
Person to do as a DIY project?

Many thanks in advance,
Julius