Is my system running efficiently?

[Steve Toorongian]

New User. Geothermal radiant heating system Contractor is out of business so I am somewhat left on my own. I prefer to be able to maintain and troubleshoot my own system anyway. System Description:

House/System: House is about 16-1700sq ft of heated space with an unheated foyer and attached sunroom. It is a ranch style house all on one level with a crawlspace underneath. The flooring is linoleum throughout. The geothermal system was retrofitted to the house with radiant floor heating coupled to a geothermal heat pump. The entire house is a single zone with the thermostat in the hallway in the center of the house. The installation was "complete" in December 2010. The geothermal heat pump is a Heat Controller Inc. Model HWW060B1C01CFC which is rated at 5 tons.The Ground Loop is a closed system with 5 100 ft long trenches filled with fused black polyethylene piping coils. There is is also about a 100ft run from the loop field back to the house with straight piping
( no coils). The heat pump is installed in a small basement that was constructed just for this purpose ( approx 10 X 20 ) The radiant heat side consists of 12 approx. 200 loops of 3/8" Onix rubber tubing by Watts Radiant. The tubing is stapled underneath the floor joists with two tubing runs in each joist section ( tube runs down curls and runs back and then through the floorboard to the next section) The tubing is insulated with foiled bubble wrap insulation stapled over the tubing runs and then 6-8 in of Fiberglass batting insulation over that. There are two Bell and Gossett (NRF-25) Circulator pumps on the radiant side. One just before the distribution manifold (supply) and one just before the entrance to the heat pump (return). Both pumps are on the high setting (III). There is also a crossover valve which is wide open allowing some water to circulate between the supply and return side or the floor loop. Another key point is that there is a Honeywell Aquastat installed on the outlet copper piping ( all copper piping is 1 inch , all soldered) the aquastat was installed by the contractor after he had a long series of problems with the heat pump tripping off during start up. His supplier who designed the system ( IRR plumbing and Heating) suggested the aquastat fix. I took some data on a couple of recent cold days to show you how things were operating: House Thermostat setting= 71deg. Actual Temp = 71 on Thermostat but 68-69 deg elsewhere in the room. The flow in the Radiant Floor loop was 8.5 GPM. The pressure in the floor loop was 27 psi. The flow in the Ground loop was 13.7 GPM. The temp difference in the Ground Loop was 47 deg F flowing INTO the heat pump and 43 deg F flowing OUT of the heat pump (measured with a clamp on thermometer). On the Radiant Floor loop the temp was 119 deg F flowing OUT and 106 F coming back IN.

Sorry for the long description. Noob so I don't know how much detail is too much.
Anyway my questions:

-Is the system is running properly and efficiently? I have certainly not been overly impressed with my electric bills which have been running as much as $260/ month in the heating season vs $100 per month in the summer ( no AC)
- Had a blown compressor motor start capacitor in Feb. Does this indicate anything?
- We were thinking of adding an approx. 500 sq ft upstairs addition to the house and have already installed another Bell and Gossett Circulator Pump and taps for three approx 200 ft radiant floor tubing loops. Can the system handle this addition?
- Heat pump manual recommended A flow rate of 3 gal/min per ton I also got the impression I should try to balance the flows on the ground loop and radiant side for maximum efficiency. As you can see from the data above I am neither balanced nor at 15 gal per min ( 5 ton). In order to best optimize my system should I try to bump up the flows and balance them and if so how would you recommend I do that? Do I need any additional equipment?
- On radiant floor side I had to open the system to install a flowmeter. There is a bubble trap and constant pressure feed valve. Is it possible I introduced air into the system and should I try to get it out? I notice the pressure gauge needle is vibrating rather than stable on one reading. Does this indicate air bubbles? I don't see any indication of air bubbles large or small in the flowmeter tube.
- Is there any seasonal maintenance you would recommend anywhere in the system? Flushing etc..?
Any and all help or suggestions are greatly appreciated.
Steve

[docjenser]

Sounds to me that you are spending $160/month on heating, which I think is very good. That also means a 5 ton heatpump is not running very much, so you should have capacity left for and addition. How much capacity? That is hard to say but it appears to me that your 5 ton system is not even running at 50%. We would need more data such as running time at certain outside design temperatures etc. What makes you think your loops are not balanced?

Assuming you have antifreeze in your source loops, your heat extraction is only 26,500 BTU, but you should see about 34,000 heat extraction. Heat capacity at those temps should be around 55,000 BTUs, which is what you push out into your floors.So I think your measurement on your source side is not correct.

I would not touch your source side, what makes you think it is not balanced? 13.7 gpm is fine for the 5 ton heatpump, you would not see much efficiency gain. Nor should you try to restrict flow with the intention to balance the loops.

Your radiant floors are not optimal. You should shoot for 10 degrees delta T, try to close the bypass valve. Bypassing your flow to the radiant system makes no sense and might explain your very high (and inefficient) temps on your radiant side. They probably designed you radiant floors like a boiler system with mixing capabilities between supply and return on the radiant side, but this is not how a geo system should be designed.
Onix is not a great material since it requires a higher supply temperature (it is rubber which is an insulator) so your system runs less efficient. It is good for boiler applications where you do not pay a penalty for higher supply temperatures. Not much you can do about it now. You would probably benefit most from an outdoor reset. 119 F supply temperature for radiant floors is very high.
The pressure fluctuations you might see due to

Where are you located? IRR supply sounds familiar. IRR is a plumbing supply chain, with limited geo design experience, which provide limited design service for installers who are not able to design a system by themselves. All with the goal to sell the equipment to them.
So the actual geo part of your system sounds OK, but your radiant system appears to be designed for a high temperature like for a boiler system.

Did I ask if you have a buffer tank for the radiant?

[Steve Toorongian]

Thanks for your helpful reply docjenser. I am in Holland, New York and by funny coincidence, in my search for a knowledgeable geothermal contractor, I saw your business (buffalogeothermalheating) somewhere in my travels in Buffalo ( where I work) and was meaning to contact you guys. I was wondering about the low source side extraction myself. The antifreeze is 25% Methanol ( I believe) As for the balance I was trying to figure out if I needed to adjust the flows on either side to maximize the efficiency. You absolutely nailed the IRR supply situation. I had the system installed by an shoddy contractor from East Aurora who screwed me over in so many ways I had to take him to court and he still never finished the job. He left me with a system that I believe is not optimized and I have almost no info about. The system was indeed "designed" by IRR and the contractor had experience with boiler radiant only. I found out everything I know by contacting Heat Controller Inc. Rather than waste more of your time on this forum I will contact you and see if we can schedule a consulting visit for you to take a look at the system if that works for you. Can you send me your name and contact info? I'm at s.toorongian@yahoo.com Thanks!

[Steve Toorongian]

Thanks for your helpful reply docjenser. I tried to send this reply yesterday but it never got posted. Anyway I see you represent Buffalo Geothermal Heating. I am in Holland ,New York. I have been looking for a contractor with geothermal experience since the crook that installed our system decided to up and leave the job before it was finished. That is a long unfortunate story but you mentioned you were familiar with IRR Supply. They did all the "design" work for my house. I have been trying to learn as much as I can about the system so I can ensure it is running efficiently. I have spoken to the technician at Heat Controller Inc a few times and I have tried to determine if things are optimal. If it works for you I would like to schedule a consulting visit with you to look over my system. If you could send me your contact info at s.toorongian@yahoo.com I will call you and try to set something up. Thanks
Steve

[docjenser]

Thanks for your helpful reply docjenser. I tried to send this reply yesterday but it never got posted. Anyway I see you represent Buffalo Geothermal Heating. I am in Holland ,New York. I have been looking for a contractor with geothermal experience since the crook that installed our system decided to up and leave the job before it was finished. That is a long unfortunate story but you mentioned you were familiar with IRR Supply. They did all the "design" work for my house. I have been trying to learn as much as I can about the system so I can ensure it is running efficiently. I have spoken to the technician at Heat Controller Inc a few times and I have tried to determine if things are optimal. If it works for you I would like to schedule a consulting visit with you to look over my system. If you could send me your contact info at s.toorongian@yahoo.com I will call you and try to set something up. Thanks
Steve

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