Cold 25F EWT

Is your ground loop at 10" or 10'? If your heatpump takes only 3 F out of the loop, there is something wrong with your refrigerant circuit, unless you have an unusual amount of flow. Was the 3F delta T in 1st or 2nd stage? I assume in 2nd stage when your house temp was dropping.

 

Options

Batoche,

Multiple unit systems is a bit of guesswork unless some monitoring is involved.

Here are a few examples of things I've come across that might be your issue:

- return ducting is in an unheated area and is coming back too cold. This forces the unit to have greater than expected run times and run in a higher stages to temper the air.
- demands on the unit are above expected/original intentions. Talking to a fellow Canuck, I can actually talk metric. An example, our recent cold snap of -20C for a few days, and a client keeping their garage at +20C during that period. The heat was not really going to a priority zone.

So, having both your units operating will help your issue it sounds.

US2616,

Sorry for having your thread poached. As to your issue, it is possible to build an actual "unpurgeable" header if the design is done incorrectly. Not saying that is your issue, but it is possible. If anything, it would come from somebody using a reducing fitting or two as they ran out of couplings at the time.

Your flow velocity needs to be 2 ft/s to eliminate air from the system. Some quick math typically shows a 1.5HP pump is good for purging up to customary 8 ton sized systems.

 

Guys, the thread is 11 months old. Lets make sure that we are not mixing things up here. The original thread deals with 4 x 1.25" pipe, which will need the purging power of 12 x 0.75" pipe. Plus the fact that 2 loops are in series, air is very likely to be locked between the 2 boreholes. Only way to solve the problem, besides wheeling in a very powerful purge cart, is to header inside and shut the other loops off during purging.

 

Bob,
Unfinished/heated basement absolutely impacts load of house.
Your system should be designed to keep up however.
You made no indication of auxilliary heat, did you not have one installed? What is the design low and balance point for your system?
Low loop temperature is not great, but not a show stopper, it may be in your area that it gets quite a bit more expensive to keep EWT in the 30's(F).
It also may be that your auxilliary heat is not working.
By the way Bob, if you are new to the forum, the mods will take time to preview your first few posts- slowing down your response time.
j

 

Thanks to Chris & Joe for your replies. Sorry if I confused things by jumping in on someone elses thread. Also the delay in publishing my replies got me confused. Now that I am in this thread I'll keep going.

It sounds like the fact that my basement is not finished and I have only 1 of two pumps in service is likely a big contributor for my poor performance. I am still baffled that at the time of startup I was able to maintain 70F even when the outside temp dropped to -15C. Also. I have built a pretty well insulated house; the walls and roof deck are insulated with 3.5" and 5" of medium density spray foam. The rim joists are also packed with spray foam and the foundation is ICF blocks. The glass is all triple pane, double gas, low E..

This morning, after running for several hours during the night in 2nd stage, the loop temp was 32F in & 25F out. The duct temp was about 82F. I think these are good numbers and yet the house temp was 67F upstairs and 60F in the basement. Fortunatel the fireplace can bring the house back up to temp. We do have a 10KW backup element but that does not appear to be kicking in. I note that I have an emergency heat setting on my thermostat and am wondering if that is a choice I have to make; run on geothermal or emergency heat. My assumption was that the system would automatically kick the electric element in if the geothermal couldn't maintain the set point after 10 minutes or so.

I don't expect any miracles here but each comment helps me to at least better understand how things are supposed to work and bring my expectations into proper perspective.

Again, I apologise if I wrongly jumped into someone elses thread and also apologise for mixing Celsious with Farenheit. My thermostat doesn't read Celsious and I'm not good and immediately converting the outside weather to farenheit.. Thanks for your comments.

Bob Shirley
North Saskatchewan, Canada

 

Not knowing your balance point, It may be the nonfunctioning auxilliary that is keeping you below set-point. The fact that 2nd stage is cycling off and auxilliary not working suggest thermostat set-up problem.
j

 

Bob, it would be good to know your duct entering air and leaving air temps as well. Measure them close to the system.

Emergence Heat - Alot depends on your thermostat. Find the manual and read how your thermostat works. I know some thermostats have a lockout temperature. For example, my thermostat will not enable emergence heat unless the outside temperature is less them 20F outside.

 

Loop temps

DGBair & Joe, thanks for your replies.

You'll have to excuse my ignorance but I'm not sure what you mean by the balance Point DG.

As for my emergency heat, I have read through the manual again and they recommend not setting the thermostat to emergency heat unless the heat pump is malfunctioning. This suggests a conscious effort to turn on emergency heat. I was under the impression that the element would kick in after a predetermined period of time if the pump did not bring the room up to the set point. Unfortunately the vendor has more-or-less abandoned me because I do not have the entire system in service. Thanks.

Bob

 

What is the brand/model of your thermostat? And can you provide any details on how it's set up?

Balance point - The min outside temp where the heatpump is still capable of maintaining the inside temp. ... (at least that's the way I think of it.) If you are below your balance point, your aux heat should kick in to provide additional heat to bring the house up to the set temperature.

 

DG, No clue at this time what the Balance Point is. The thermostat is a NextEnergy NE-32-2000. Not much to the User setup that I can see. I choose my Mode, in this case heat, and specify how I want the fan to run, Automatic. I think that the setup that you are referring to in this case is the configuration of the CXM controller board in the heat pump. That is where the thermostat is connected via an 8 wire cable. You got me curious now and I'm going to try and figure out how the jumpers and DIP switches are configured. if I learn anything I'll let you know. Thanks.

 

http://www.haliburtongeothermal.com/resources/Documents/7.2 NE-32-2000 Thermostat User Guide.pdf

Looks like only a 2-stage heat thermostat. Which means your don't have a 'W' wire (sometimes called 'W1') connected. The 'W' wire is what will enable your aux heat if your heatpump can not maintain the set temperature.

 

nice catch

 

How sad that the installer is so incompetent

 

You are confusing emergency heat with aux heat. Aux heat is the third stage of heating, it is engaged by the stat after first and second stage are running and not able to satisfy the stat. Emergency heat bypasses the compressor circuit altogether, engaging the strip heaters ONLY.

Bergy

 

You are of course correct Bergy... I should have said Aux heat in my previous append..