Hey all, I've got a 2800 sq.ft. house (2050 sq.ft. 2 story, 768 sq.ft. addition) with full basement being powered by a 3 ton and a 5 ton Climatemaster Water to Water Tranquility TWM Series geos with a closed horizontal ground loop and an 80 gallon storage tank. The house has 8 zones (5 hydronic radiant floor zones and 3 air handlers). I'm wondering about the best approach to go about verifying that the system is operating as efficiently as possible. I already have a real time whole house hydro meter from efergy installed, and it seems like the geo(s) are running a lot, since it feels like whenever I walk by and glance at the meter, it is running at 15kW or higher depending on what else is running. Usually the demand is met by only one of the geos (running in flip flop configuration). Hydro is expensive in Ontario and so far we have no solar supplement (although that was a future idea). Considering there are so many zones, it is likely that at any given time, at least one may call for heat and not long after the geo is working to top up the storage tank. I have considered getting an insulation wrap for the storage tank. I've wondered if a 2nd storage tank to increase storage capacity would be more efficient. I've thought about getting additional monitoring hardware to more closely watch the geo system itself. I was wondering if there was some advice out there on best next steps?
Your desire for knowledge reminds me of my thoughts when I converted to geothermal from a hydronic oil system. Are you willing to become more involved in your system? Monitoring hardware? There are several I know of, but www.welserver.com was my choice and is referenced here quite often. My site is http://www.welserver.com/WEL0899, as a simple example of what's possible. Here's a performance document I found helpful https://geoconnectionsinc.com/resources/forced_air_efficiency_measurement.html It's for water to air systems but it should help you get closer. Good luck!
http://welserver.com/WEL0877/ Hydronic geo is an art form. They can be heaven, and they can be hell. The culprits for inefficiency are usually high pumping power and high load water temperatures, and sometimes mixing valves in the individual zones circuits are the culprit.. More details are needed to provide help and advise. Start with pictures and layout of your system. And pictures. Post them here. Also how does your distribution manifold look like? How many pumps do you have, what model of pump(s) your water through your loops, and what is the temperature at your storage (buffer) tank. No need to increase storage capacity, this is to buffer the radiant system, not to increase your stored capacity.
Hi guys, thanks very much for your replies. Busy time of year so just getting back to this now. Stickman, I did see the welserver and looked at it briefly... it seemed a bit intimidating. docjenser, I will try to answer your questions as best as I can. Please ask more or clarify if I don't provide what you need. I've attached a plumbing diagram, created by me, that maps the connections as best I could (I might not have all the arrows going the right direction but I did what I could). I also attached a few pics. Early pic during installation shows a general layout, and later pics show more finished result, but the small space is quite busy now with lots of pipes and an air handler in front. The zone pumps are Grundfos UPS 26-99FC (set to low speed) or UPS 15-58FC (set to medium speed). The system is controlled by a CPU-0500 unit, with an outside temperature sensor that sets the storage tank temperature to a variable set point (ie. hotter setpoint when outside temp is colder), for instance, tonight the outside temp is 0 degrees F and the buffer tank setpoint is 110 degrees F. Thanks.
As I said, the reason for inefficiency is high pumping power and high water temperatures, which is the case here. What are the pumps (they are grundfos), what is the model number, on the flow center, the white canister next to the heatpump which has 4 black pumps on it. ANY idea how the loopfield is configured?
The black pumps on the flow centre are grundfos UP26-116F. It is described as 4 Pump QT-EA Flow Center - Grundfos 26-116 Single Speed Pumps (2-2EA-SS-230QFC-M) on this site: https://www.bdmfginc.com/product-single/flow-centers/qt-ea-flow-center The loop is a horizontal loop consisting of a single header trench, which provides 2 lines coming into the house. Connected to that header are 8 600' loops located in 8 trenches that 300' long extending out from the header. The trenches were supposed to be around 6' deep and 4' wide. Loop is a water ethanol mix. In March 2011, it was reported: Source Water In: 37.8F Out: 32.6F Source Pressure In: 30PSI Out: 20PSI Load Water In: 100.2F Out: 105.7F In June 2014, it was reported: Source Water In: 53F Out: 46.4F Source Pressure In: 20PSI Out: 10PSI Load Water In: 71.5F Out: 77.3F Hope that helps.
the 26-116 is a very inefficient pump, each consuming close to 400 watts (x 4). Then there are more pumps for the zones, also very inefficient.
Interesting. so are you suggesting that the flow center should be replaced? Or just the pumps on the flow center? or all the pumps?
A variable speed flow center would help reduce geo side pumping costs. Even more improvement could be made by replacing all your load side pumps with zone valves and using 1 or two delta-p or delta-t variable speed emc pumps. The big variable speed pumps are expensive so it might make more sense to split them in to two groups, each with their own ALPHA 15-55 variable speed pump. Have tried running your 3-speed load pumps at the lowest speed? If the zone can be satisfied at the lowest speed on design day you will save pumping power year round. You could bump up to a higher speed as needed. This is no cost alternatives. A new load center and switching to zone valves would cost some money. Can you describe how exactly how your units are staged and if outdoor reset is used?
I'm not sure if the above answers your question about "outdoor reset". If not can you clarify it? I bought this system, I didn't design it, so may not be familiar with all the vocabulary. Regarding staging, I believe the CPU-0500 is set to "2 Stages of ON/OFF Boiler with Rotation" and rotation is defined as one boiler exceeding the other by 48 hours of run time.
If that system was installed today by an evolved contractor, it would definitely have variable speed pump(s) and zone valves on the load side. The numbers for a variable speed flow center might not be as good, but if it was my house I would go for it. It is interesting that two units with different capacities are set up to rotate based on run time, but it might have a more sophisticated scheme. I like the idea of two different sized units but would treat them as stages based on outdoor temperature where the lower capacity one would be run down to a certain outdoor temperature when the larger one would take over until it got down below a certain temperature at which time both units would run if needed. This would put a lot more run time on the lower capacity unit but would be most efficient in the long run. This may take custom control and programming, but there are nice ones that are easy to program for under $150. To help even out run time, the larger unit could be directly piped to and be the only one to feed the indirect water heater, bypassing the buffer tank during calls for hot water production. The smaller unit could be piped in as well, but as a fall back in case the larger unit is out of commission. All this said, any change is going to cost money, so depending on electricity prices and/or availability of alternative fuels, it may make sense to leave it as is unless there is some increase in comfort for the home that can be achieved as well. Changing out the pumps for variable speed pump(s) and zone valves is a possible DIY job. Using a press system to avoid soldering would really help. If you wanted to do that or hire it out, you could get some good advice over at heatinghelp.com.
Yeah, I believe when the system was first started, it used the 3 ton as stage 1 and the 5 ton as a stage 2, and as you'd expect, the stage 1 got alot more use and when the stage 2 was called and broke down, it was suggested that running them in rotation might be better so you would avoid the situation of one of the units sitting idle for long periods of time, only to break down when finally called upon. Maybe that was an over-reaction to a one-off break down, I dunno. I could explore the idea of going back. It is unfortunate I didn't learn of these opinions sooner. A while back, several of the zone pumps were replaced because the original contractor had wired their "control center" using relays to control the higher voltages required for the pumps and we decided to replace that control center with the 2 electronic Zone Relay units in the picture because the manual relays were prone to failure (or worse, sticking in the on position). This required the replacement of a few zone pumps because the original contractor had used a combination of 115V and 220V pumps (probably just because that is what the supplier had available on the day they needed them) and the Zone Relay units could only drive 115V pumps. That, instead, could have been a good time to investigate swapping the zone pumps for zone valves instead. I am curious about the idea of trying to run the zone pumps at the lowest speed possible. What would be the correct way to test/ensure that the demand for the zone is being satisfied properly at those lower speeds, without subjective guessing such as, "I guess it still seems warm?" kind of testing. Also, would running the zone pumps at the lowest possible speed apply equally to both air handler zones as well as radiant in-floor zones?
I am curious about the idea of trying to run the zone pumps at the lowest speed possible. What would be the correct way to test/ensure that the demand for the zone is being satisfied properly at those lower speeds, without subjective guessing such as, "I guess it still seems warm?" kind of testing. Also, would running the zone pumps at the lowest possible speed apply equally to both air handler zones as well as radiant in-floor zones?[/QUOTE] "I guess it still seems warm?" when it is your coldest day or otherwise on very cold days the thermostat won't satisfy are your best options. I am not sure about the air handlers as you do risk them blowing coldish air.
Running zone pumps at lowest speeds - we often use delta T pumps. You set the delta between in/out to be about 20F. That's somewhat of an industry standard that is used in initial design calculations to determine the w/m2 (btu/ft2) heat flux required to dump heat into that zone. If you slow down the flow past that, you are essentially going to have cold spots on the end of the circuits for that zone.
Attached is the most efficient radiant design we could come up with twin water-water heat pumps, including DHW, heating and cooling via hydronic air handlers. Note the central variable speed circulation pump for the zones, the small circulator pump between each heat pump and the buffer tank, and the zone valves for every zone. 3 way valve for indirect DHW tank. On the source side there is one variable speed circulation pump as well. Chris, I respectfully disagree with you that the delta T should be 20F on the load site between supply and return from the zones. We usually run them between 5-10F max., preferable less than 5F delta T. That way you do not have to get the supply temp so hot, and you save on efficiency on the compressor side. With variable speed DC inverter pumps, and low pressure drop, you have much lower pumping power nowadays, so you do not get penalized very much for higher flow. 20F delta T was during the old boiler age with high supply temperatures, not for high efficient low temp geo systems.
