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Spoke to the city, currently have a 5/8" tap with 3/4" main. To increase to a 1" tap would be $46000, so that is not going to happen. I am trying to get the actual city water pressure, but I am still wondering if instead of going from a 5/8" tap to a 3/4" main, going to a 5/8" tap to a 1" main would do anything since the city water pressure needs to be reduced through the water pressure regulator?
City pressure at the street is 136 psi. Setup is actually a 3/4" line to a 5/8" meter to a 3/4" main. City is telling me to crank up water pressure even higher, which doesn't sound right to me. However just wondering for a test, how high I can raise the water pressure to see if I can get any more flow through the rinnais? |
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Yes, City fees are high no matter where you are. However, you don't have to have the meter upgraded. Just upgrade water main. I would install 5/8" -to-1" increasing bushing right on the water meter and continue with 1" line towards the house. You can increase pressure as high as you want. I don't know what kind of pressure regulator you have. Typical residential pressure regulator, like Wilkins 70 and Wilkins 600 go up to 75psi maximum. I would suggest that you use Braukmann pressure regulator that will allow you to turn up your pressure up to 300psi. Also, Cash Acme makes such a regulator. I don't think you can get those in Home Depot, but you can get it in pro-plumbing supply house, like Ferguson Enterprises, or Hirsh Pipe and Supply. I think Hirsh will ship out. You can Google them, both companies are well know suppliers. Increasing pressure will present you with new set of problems. One of them is noise caused by friction. You may be hearing water as it travels through pipes. Depending on how is your house plumbed, it may be too audible. Also, your pipes may knock and bang caused by changes in pressure as you open and close valves. That is especially true with washing machine (solenoid valve) and toilets. You may also notice that some fixtures are not operating properly ( or harder ) due to increased pressure on closing mechanism. But give it a try. See if you can achieve the desired water flow... Let us know how you did... |
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As a test I turned off toilets and ice maker so nothing would explode, and turned up water pressure to 130psi. Flows through the rinnais were 4.6 gpm through 1 rinnai turned on 7.8 gpm turned off. 4.4 gpm each through 2 units turned on 4.4 gpm each turned off and 3.0 gpm each through 3 turned on and 3gpm turned off.
Just curious to avoid major excavation, what if I stayed with the 5/8" meter to 3/4" main for 30" until it entered the house, and then switched to 1" pipe with a 1" pressure regulator downstream of the switch from 3/4 to 1". How much of a difference would the 30 feet of 3/4" copper make? [QUOTE=Milo Dolezal;1672389]Yes, City fees are high no matter where you are. However, you don't have to have the meter upgraded. Just upgrade water main. I would install 5/8" -to-1" increasing bushing right on the water meter and continue with 1" line towards the house. |
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Rinnai says that the supply has to be reduced to 3/4" before entering the unit. Are you saying I should run 1" to the rinnai, reduce to 3/4" into the rinnais and then 3/4" out of the rinnais and then increase back to 1" for the run to the mixing valve and then switch back to 3/4"?
[QUOTE=Milo Dolezal;1672185]Jimbo, that water main is definitely undersized. You should have at least 1" water main and continue with 1' pipe all the way to feed the first 2 bathrooms, Rinnais and washer. Then you can reduce to 3/4". You can call your Building Dept./ Plumbing engineer and he'll tell you right away what size pipe you need. So this would be the case if I kept the 3/4" copper? Do you think I would have no problems at all if I made the switch right at the meter from 5/8 to 1"?  Originally Posted by Milo Dolezal
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Run 1" all the way. Do not reduce. Feed all 3 Rinnais out of 1" pipe. Cap 1" at the end. See pic... Originally Posted by jimbo770
Jimbo: I have a meeting in 20 minutes. I will have to run for now. I will log in later in the afternoon... Thank you. Milo |
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In this example, is the 1" hot main you mention downstream of the rinnais? If so are you coming out of the rinnais with 3/4" and then going back to 1". Also what kind of flow are you getting through the master shower with all 5 heads turned on? Finally, how big is the water meter?
Is there a way to determine how much my flow will increase if I run a 1" main from the meter to the rinnais, and 3/4" hot to the master shower? I am open to replacing the main, but since it will probably be a gigantic nightmare, I'd like to have some idea how much the benefit will be. ( Presently, we are working on very similar house. It is 3,096sq feet, 4 baths, 2 Rinnais. Rinnais are not together: One is direclty behind Master Bathroom and serves only Master Bath. The other one is on the other side of the house supplying rest of the house with hot water. Blueprints asked us to run 1 1/4" cold water line starting at the meter, unreduced, through entire house reaching every bathroom and both Rinnais. Hot water is 1" main run with 3/4" branches to each shower valve. Master Shower has 5 shower heads. Pressure here is 115 psi reduced to 55 psi. ).[/QUOTE] Also, I am planning on adding a recirc pump with a small 5-6 gallon electric hot water heater, and probably the grundfos comfort system pump, using the cold water line as a return. Will this negatively affect my flow rate? Just wondering since you and the engineers at rinnai asked if one was installed? |
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Installing circulation pump with a small elec. Storage tank should not have effect on water flow - as long as you don't connect it before shower connections. It has to be connected on the return, preferably close to Rinnais. Also, make sure you purchase proper pump, like LAING or Gronfo made specifically for tankless heaters. Ordinary pump will not do the job. |
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Milo,
Sorry I double posted so I don't know if you saw this post. Thanks, Jim In this example, is the 1" hot main you mention downstream of the rinnais? If so are you coming out of the rinnais with 3/4" and then going back to 1". Also what kind of flow are you getting through the master shower with all 5 heads turned on? Finally, how big is the water meter? Is there a way to determine how much my flow will increase if I run a 1" main from the meter to the rinnais, and 3/4" hot to the master shower? I am open to replacing the main, but since it will probably be a gigantic nightmare, I'd like to have some idea how much the benefit will be. ( Presently, we are working on very similar house. It is 3,096sq feet, 4 baths, 2 Rinnais. Rinnais are not together: One is direclty behind Master Bathroom and serves only Master Bath. The other one is on the other side of the house supplying rest of the house with hot water. Blueprints asked us to run 1 1/4" cold water line starting at the meter, unreduced, through entire house reaching every bathroom and both Rinnais. Hot water is 1" main run with 3/4" branches to each shower valve. Master Shower has 5 shower heads. Pressure here is 115 psi reduced to 55 psi. ).[/quote] |
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Jimbo: excuse the timeliness of my response to your last post... I am enclosing sketch of our ongoing project to better illustrate my explanation. The project is scheduled for trim installation for 1st week in June. I do not have some of the details you are asking. Usually, HomeOwner hires her own architect who in turn has her own engineer to work out the details of the project. All we get is a spec mechanical page in a set of blueprints that gives us all final dimensions. Detailed calculations, like Flow, or methods used to arrive on proposed pipe sizes are not included... In the case of our ongoing project, we have 1 1/2" meter split into two 1 1/4" water mains. One is going to Sub-Meter ( I do not show this in the sketch) and the other continues to the house. House is a large, single story, ranch type house and is about 97 feet long. There are 2 Rinnais: one on one end of the house supplying hot water for whole house - except master bathroom. Main line continues unreduced across entire length of the house and terminate on the other end with connecting the second Rinnai. Connections to the Rinnais from the main are done by 3/4" risers directly from the 1 1/4" main. Risers on both Rinnais are about 24" long. Each Rinnai delivers hot water from 3/4" x 24" piece of pipe into 1" main hot water run which in turn continues to each plumbing fixture. ( 1/2" branches for sinks and tubs, 3/4" for showers. In case of Master Bath, the second Rinnai is only 8" away from the first shower valve ( on the same wall, shower valve is directly behind Rinnai ). Master Bath has 5 heads. All are Grohe, including 16" jumbo rain shower head. All heads are rated at 2.2 gln/m flow. (11 gpm demand / total ). I will test it after the trim is installed. As of now, I cannot expand on the gallons per minute flow since I do not have this info at this time... You may place phone call to City Mechanical Engineer with the flow question. (S)he should be able to give you this info in a minute. You will need to supply the following info: 1. Total Developed length of pipe 2. Pressure at the meter 3. Pipe (material) used + its size 4. How many 90's, 45's etc. You have to estimate here... If my memory serves me well, you use "Hazen-Williams" method or "Manning" Formula to figure it out. Then, you have to adjust for friction loss and pressure loss to get Flow Rate (gpm) and/or Velocity (ft/s). But not sure here. It has been "few" years and I am not a mechanical engineer... :D In my area I cannot remember the last time we used 3/4" as main water supply for residential house. 1" is minimum and widely used, 1 1/4" is not that uncommon when used, and 1 1/2" is used on oversized houses. Sizing is important. Correct size of pipe not only delivers required volume of water across the house but also cuts down on friction noise during delivery. Today, and w/o giving full story, I asked few installers their opinion to your problem. I wanted to see their first response. Most of them said "inadequate gas supply". ( Rinnais produce less hot water when they don't have enough gas supply ), as well as they questioned the 3/4" pipe... Rereading your previous post that includes the test numbers, I do not understand the following: If you - lets say - run 2 Rinnais / hot water only / you should max out the water flow at your Eco valve. Instead, you are getting only 2 x 4.4 glns. That bugs me. Rinnai engineer told me that with 2 - 94LSi Rinnais running simultaneously you should be getting 18.8 gallons, a volume your Eco valve can handle. Here is where I suspect inadequate pipe size... Time to call your engineer. I am sure (s)he'll know in a second what is inhibiting your water flow... Please, come back to let us know what you've found out.. Regards / Milo |
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OK here's the latest. The city I live in will not allow me to increase the water main size to 1" without increasing the meter. They only allow an increase of 1/8" from meter to main.
Speaking with Hansgrohe today, I found out that the ecomax rated at 20 gallons, needs close to that volume to operate properly. Also the hot and cold pressure have to be close(I forget the exact psi he mentioned) or the mixer will also start acting screwy. I can swap out the ecomax with the ecostat which is rated at 13.2 gpm which will help the flow issue, but we are still getting a pretty big pressure loss through the rinnais. So here's my question, could I T off the cold water main upstream of the pressure regulator, and run either 3/4 or 1" pex directly to the rinnais? This would shorten the run, remove 6 or 7 elbows and I am hoping deal with some of the pressure loss through the rinnais since we would have 120+/_ psi going into the rinnais. Also since it would be on the hot water side, the icemaker, toilets etc would not be affected by the higher water pressure. On another note. The water pressure regulator is a conbraco. It says max inlet pressure is 400 psi with an operating range of 25-75psi, however if I crank it down all the way I can get static pressure of 120+psi. Why is that? Finally, With static pressure set at 80 psi I am getting a pretty big pressure loss with the rinnais turned on. Each unit will run at 4.5 gpm. Starting at 80 psi static, if I turn on 1 rinnai pressure drops to 65 psi, 2 units on 60psi 3 units on 55psi. I am wondering why there is such a large pressure drop since the street pressure is 136 psi. Do you think one of the other regulators you mentioned would maintain a more constant pressure as the units are turned on? |
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Jimbo: before I respond to your latest post: can you post a photo of your 3 Rinnais installed ? I will be meeting with Rinnai rep on the 30th. I will print out our conversation and present it to him. Hopefully, he will be able to come up with solution... You should not read pressure higher than 75psi behind regulator. Otherwise, your regulator is not working properly - or is installed backwards. It is always good idea to run pipe as directly run as possible. Every elbow will present you with pressure loss - and lower pressure will effect volume delivery to your fauct. Same with long length of pipe. You will be losing pressure with long runs. Pressure loss in these cases is not significant but some loss is there. If you want to run new dedicated Pex line, don't use 3/4". Go with 1". Jimbo: what area are you in ? |
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Milo,
I am in Colorado. I will post some oictures this evening. The regulator is installed properly (arrow is pointing the right way) I have a call into conbraco to see what they say. Here's some more info that I have gathered. If I run the Rinnais with hoses hooked up to the drain valves (taking everything downstream of the rinnais out of the equation) I get the rated flows on all 3 units (approx 4.5-5.3 gpm depending on rise) If I turn on all the 2 handled faucets in the house on (no mixing valves, and there are 5 sinks) I get 7.5 gpm which is exactly what they are rated for. If I put a demand on the Rinnais greater than 10.5 gpm (going through the actual plumbing in the house, the rinnais will max out at 10.5 gpm which I can't for the life of me figure out. I did the hazen williams equation and got cold side - 9.08 ft/sec - 9.5 psi/ft h2o - 4.1 psi head loss through 100 ft of pipe to the aster shower. Hot side - 9.08 ft/sec - 15.7 psi/ft h2o - 6.8 psi head loss through 160 feet of pipe, but I have no idea what these numbers tell me. I have ordered an ecostat mixer which may help, but I won't get that for a week or so. Regarding a separate run to the rinnais. Do you think it would be OK to run a 1" pex line directly to the rinnais using unregulated water (upstream of the regulator) and if so and I install a recirc system using the cold water side for the return, will there be a problem since the hot water side would be unregulated and the cold side would. |
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The Instantaneous Gas water heaters have a flow control valve that modulates to reduce the flow rate through the water heater in order to maintain the required outlet temperature. This is one of the drawbacks of instantaneous water heaters. If the flows change the outlet temperatures change. To counter this newer models have controls to modulate the outlet HW flow to help maintain the temperature. In the winter time the incoming cold water temperatures drop especially in northern climates. In order for the instantaneous water heater to maintain the hot water outlet temperature it has to slow the flow of water down to allow enough heat to be added to raise the cold water temperature from 40 degrees up to the desired temperature.
I find it much easier and cheaper to just purchase a 50 gallon storage type water heater for less than one-third the cost of one instantaneous heater (about one tenth the cost of three instantaneous gas heaters) Then there will be plenty of hot water and no hassles. Ron George |
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Originally Posted by Plumbing Expert
I am going to swap out the regulator on Mon. The local plumbing distributor said the conbraco is limiting the flow considerably and with a different unit (he recommended the watts 223) which is a super capacity unit should increase flow as well as maintain a more constant pressure as demand is added. I will let you know how it works out. Here are the pics |
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