Hi...

I have a Janitrol heat pump (I don't know the model number) controlled by a Robertshaw thermostat (model #9520).

I am having a problem with the heat pump warming the house to the normal setpoint for comfort (say, 70 or 71) during the day but the heat pump continuing to run. By continuing to run, I mean the whole system, inside and outside units (fan, compressor unit).

Today, we are having temps in the mid- to upper-40s. I had I lowered the setpoint to 66 and the unit would turn itself off. However, if I raise the setpoint, the problem with it continuing to run recurs.

On especially cold nights (in the 30s or even into the high 20s), the heat pump will run for hours without cutting off and it doesn't appear that the auxiliary heat ever comes on.

I called an HVAC service to come out Monday (Christmas Eve) and the tech looked things over. He said the refrigerant level, compressor, defroster, heat strips, etc. all seemed fine. He pressed the reset switch on the thermostat and said that might clear it up. If not, he said I may need a new thermostat.

He explained how auxiliary heat worked and said that if it's cold enough outside for the heat pump to not warm house sufficiently to shut the system off, the auxiliary heat should kick in to help to reach the setpoint. (He also said that if the heat pump warmed the house to setpoint, but the unit continued to run for a lengthy time, the auxiliary heat should come on long enough to help the unit shut off.)

Today's example, as I type: I had the setpoint at 66 since this morning. While reading over this site, I reset the thermostat to 69. The unit has raised the temp to 69, but now the heat pump is continuing to run and there is no sign of the auxiliary heat coming on, although the setpoint of 69 was reached 15 minutes or so ago.

It sounds reasonable to me that this may be a thermostat issue, but I wanted to see if I could find any other information/assistance that might help confirm that diagnosis before I purchase a new thermostat.

The tech also advised that if I go with a new thermostat, to stay away from Hunter and preferably go with a Honeywell. Your thoughts on that would be appreciated as well.

Thanks!

--Paul

UPDATE: about 25-30 minutes after reaching the setpoint of 70 this afternoon, the unit just shut off.

Honeywell all the way.
Someone needs to check your aux/strait electric heater circuit unless you already did that. Turn the stat all the way up and see if the electric heat turns on. If it does it could be the stat. If it does not it could be the stat or a component in the electric heat circuit.

Quote:

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Originally Posted by hvac1000

Honeywell all the way.
Someone needs to check your aux/strait electric heater circuit unless you already did that. Turn the stat all the way up and see if the electric heat turns on. If it does it could be the stat. If it does not it could be the stat or a component in the electric heat circuit.

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Thanks for the reply.

I forgot to mention in my original post that if I raise the setpoint 4 or 5 degrees, the auxiliary heat will kick on. I have checked that myself and the tech that came out Monday did as well.

Looks like just the thermostat. REMEMBER (write down) the colors of the wires and where they came from so you can change out to a new t-stat with little or no problems.
Make sure you get a 2 stage heat and one stage cool heat pump thermostat.
You can check the beginning of this board under sticky notes to help with thermostat wiring.

Quote:

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Originally Posted by hvac1000

Looks like just the thermostat. REMEMBER (write down) the colors of the wires and where they came from so you can change out to a new t-stat with little or no problems.
Make sure you get a 2 stage heat and one stage cool heat pump thermostat.
You can check the beginning of this board under sticky notes to help with thermostat wiring.

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I was looking at various thermostats on a web site - prothermostats.com (although I will purchase the thermostat at Lowe's or Home Depot) - and was able to read the installation instructions for the different Honeywell models up for consideration.

In the installer instructions, there is a section where parameters have to be set inside the thermostat itself, such as "Changeover Valve (O/B)" (mine should be set to "O") and "Stage 2 Heat Cycle Rate/Auxiliary Heat Cycle Rate". A couple of questions I have that I imagine you can help me with:

1) Are these parameters set after the thermostat is wired and the power from the main breaker is turned back on? (Or should it be done on battery before the whole system is powered?)

2) For the "Fan Control (heating)", I presume I use the setting for "electric furnace (thermostat controls fan in heating)". Correct?

3) For the ""Stage 2 Heat Cycle Rate/Auxiliary Heat Cycle Rate", I presume I use the setting for "electric furnace"? Correct?

Given that I've never replaced a thermostat before (although it seems pretty straightforward), I wanted to be cautious and ask these questions to ensure I don't make a mistake.

Thanks for all your help!

--Paul

First go here to the honeywell site. In the lower right side you can type in the model number you are interested in. There is a bunch of info there including the wiring diagrams and a step by step instruction for your model.

Default - Honeywell Environmental And Combustion Controls

1 usually you can program a honeywell on batterys while sitting in a comfortable chair having a coffee.

2 You might find that there is a setting for heat pump selection on the instructions for the fan.

3 Yes

Unless you are in a hurry you might want to look at a few different Honeywell thermostats.

Catalog

Thanks for responding again.

I've looked at the Honeywell site and have found quite a variety of thermostats that will apparently work with my system (2H/1C).

I wanted to double check on the fan setting because the only two options I found on most of the models is "0" for "gas or oil furnace" and "1" for "electronic furnace", with no option for heat pump, although the models are for up to 2H/2C heat pumps.

I hope I'm not being a bother, but can you tell me why Honeywell breaks the thermostats between do-it-yourself and professional installer models? I notice the professional models (such as the PRO or FOCUS models) seem to each handle a wider variety of heating/cooling configurations, but wonder if there is a good reason why I should stick to the DIY model or, if I were to consider a professional installer, why I would go with the professional installer models?

From the wiring instructions I see, I don't see anything any more difficult, as long as I'm sure to get a model that handles my 2H/1C configuration.

Thanks!

--Paul

Quote:

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Originally Posted by hvac1000

First go here to the honeywell site. In the lower right side you can type in the model number you are interested in. There is a bunch of info there including the wiring diagrams and a step by step instruction for your model.

Default - Honeywell Environmental And Combustion Controls

1 usually you can program a honeywell on batterys while sitting in a comfortable chair having a coffee.

2 You might find that there is a setting for heat pump selection on the instructions for the fan.

3 Yes

Unless you are in a hurry you might want to look at a few different Honeywell thermostats.

Catalog

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The pro series thermostats have a program mode that has to be entered by 2 keys being pressed at the right time. Once in the program mode follow thur the codes to make sure your set them right with your system. If you have any questions lean toward the factory setting. I have a code book and can help if you need any help. You should be able to install any of them if you can follow the easy to read diagrams in their installation guide.

A local HVAC parts house should be able to sell you a Pro 8000 stat. The dehumidification one is the one I lke. This way you can see the humidity level in your house. Price around 200.00

The problem you might run into buying a thermostat at a real HVAC parts house is warranty. Since you are considered a non pro they might not want to warranty the product. Also read the fine print on the pro warranty. Many times it will say warranty void if not professionally installed or something like that. Many times they will want a bill from the HVAC company on there service invoice to you that says they installed the thermostat for you. Just a thought.

Quote:

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Originally Posted by hvac1000

The problem you might run into buying a thermostat at a real HVAC parts house is warranty. Since you are considered a non pro they might not want to warranty the product. Also read the fine print on the pro warranty. Many times it will say warranty void if not professionally installed or something like that. Many times they will want a bill from the HVAC company on there service invoice to you that says they installed the thermostat for you. Just a thought.

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I think I'm going to go with the Honeywell "RTH7400D 5-1-1 Day Universal Programmable Thermostat". I'll pick it up tomorrow and put it in.

From looking at the wiring in my current thermostat and the wiring info I have found on-line (Honeywell's PDF file with installation instructions), this seems pretty straightforward.

Thanks for all the help today. I'll let you know how it goes.

After price checking at Lowe's and Home Depot, I decided to go with the Honeywell RTH7500, 7-day programmable. It was $15.00 cheaper at Lowe's than at Home Depot and only $5.00 more than the RTH7400 (at both Lowe's and Home Depot) I had been looking at. And -- Lowe's had a deal where any purchase over $50.00 would include a $10.00 coupon good for my next purchase.

Installation went easy and smooth. I owe thanks to Honeywell for engineering a good user interface and installation instructions, to the tech who gave me some tips when he came out the other day, and to you hvac1000. You really helped me put together the various pieces and was responsive in your answers so that I felt comfortable doing the thermostat replacement myself.

Thanks for all the help!

Glad to be of service. Happy New Year

Best advice you got was to stay away from Hunter,, haven`t see a goodone yet

Best advice you got was to stay away from Hunter,, haven`t see a good one yet

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Originally Posted by wmproop

best advice you got was to stay away from Hunter,,,,,haven`t see a good one yet

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And I did. Got the Honeywell.

Thanks.

Yeah so go buy a Lowe's brand hunter cheapy thermostat that does not half work. That a better Idea.