Water to Water Geothermal heat pump replacement with lp boiler
I need to replace my waterfurnace water to water geothermal heat pump (EW042) and the prices I've received to replace are eye popping. The lowest quote I've received was $$$$$. This was to replace with a waterfurnace 5 series 3d, geoflo unit and add a 80 gallon buffer tank (original system wasn't installed with one). I am hesitant about replacing the system because it has never performed very well and it's really noisy ( installed in basement directly below the master bedroom). Output has been nowhere near spec and the installing contractor could never give me a straight answer as to why. We have a 16kw backup electric boiler that switches on at an outdoor temp of 30 degrees otherwise the heat pump cannot keep the water up to temp at 110 and will go into freeze protection.
My current setup is 4" slab in basement and 1.5" gypcrete on the 1st and 2nd floors. All 1/2" pex. 5 zones using 007 circulators. 2 zones in basement, 2 zones on 1st floor and 1 zone on 2nd floor. I didn't have a heat load done when we built in 2007. I had energy vanguard do a manual j and i did have a blower door test done at beginning of 2025. Energy Vanguard came up with 25000 btuh roughly for whole house. I did my own awhile back and came up with 34000 btuh for whole house.
So I really can't afford $$$$$ right now. So I'm wondering if it would be worthwhile to switch over to a lp combi boiler or lp boiler with dhw? Or hang on a little longer and save some more $$$ and replace at a later date. Ive received a price of $7500 for the combi boiler working with current circulators and piping.
I would probably just install a unit for ac using the current ductwork.
Does anyone have any ideas of the best route to go?
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geo should be much cheaper operating then straight electric.
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I'm asking if it makes sense to replace with propane boiler.
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what’s the cost of Electric
What’s the cost of Propane
https://coalpail.com/fuel-comparison-calculator-home-heating
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Please edit to remove pricing, we can't discuss prices of services.
Perhaps the most economical option would be to find someone that knows what they are doing to fix it.
Keep in mind with the mass of the slabs and the nature of the geothermal source, this is designed to run continuously at one temp, it won't work well if you try to run it with a setback thermostat.
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Electric is .16 kwh.....propane is $2.50 gallon
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That's the issue with where I'm at south of Pittsburgh. There is only one geo guy around here and he insists on replacing and not attempting to fix what was done previously. Hence the predicament I'm in.
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find a different contractor
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At those rates GEO is 1/3 cheaper
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if the original installation was not designed properly, lack of adequate loops or well for example.
Maybe the load is larger than anticipated?Or the installation was botched?
new replacement or repairs may not get what you expect
I would do some number crunching. A load calc as step 1
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
Sounds like you have a load of 25-35K with a 42K unit. It may be oversized.
If the unit is ok other than it doesn't perform well I would find out why it is not producing. WSHP don't have to defrost in the winter so are much better than an air source HP.
Believe me I am not a HP guy I am a boiler guy, but I wouldn't toss it yet especially versus propane. I did some water furnace units and thought they were well made I was impressed by them.
The other issue is I would not replace the WSHP with a new one without finding out what the issue is.
Why not call Water Furnace and see if they can recommend someone?
Tell them it never worked right and you MAY be willing to replace it but are reluctant since it didn't work well and you might go for a boiler.
Maybe @RayWohlfarth
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"We have a 16kw backup electric boiler that switches on at an outdoor temp of 30 degrees otherwise the heat pump cannot keep the water up to temp at 110 and will go into freeze protection."
This indicates to me that most likely the well is undersized. Or maybe the piping to the well, in any case it's not able to provide enough earth-temperature water to meet the heating load. If that's the case then there's not much that can be salvaged.
An outdoor temp of 30F is not terribly cold, if you're switching to the electric boiler you're probably using a lot of electricity.
A propane boiler is probably going to have the lowest installation cost. Your breakeven COP is around 1.5 so even an air-source heat pump might have lower operating cost. If you want to keep the heated floor you'd be looking at an air-to-water heat pump, which is going to have some of the same issues as a water source in terms of high installation cost and few options for installers.
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just because it is switching to electric doesn't mean it has to…
if @RayWohlfarth will work on it or knows someone that will, go with him.
of course if it is just completely engineered wrong, he can't change the laws of physics and it may not work with a propane boiler either if that part is wrong.
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I contacted the company that installed the wells and he said he drilled (3) - 180' wells with 3/4" pipe. They are manifolded together out in the yard to 1 or 1 1/4" pipe and come into the basement as 1 supply and 1 return. The geoflo unit is a 1 pump pressurized unit.
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If you are switching to resistance heat often, your COP or efficiency may not be what you assume.
Some installers add a small Kwh meter on the HP to see what it is actually consuming.
If the resistance is in fact being used or over used, the LP starts to look better.
Some GEO issues are not easily fixed if you have a well, pond, or loop field that is not up to the task.
All this is knowable with some number crunching.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
I recently purchased an emporia vue energy monitor. I'm going to get it installed and at least can monitor the energy usage.
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Properly designed and installed you would be hard pressed to find a more efficient heat transfer machine.
Slab and gyp pour radiant should ba a perfect match for that HP.
Did you try Water Furnace directly. Most manufacturers try hard to support their products or can refer you to qualified help.
Are you getting on 20 years with this system? Did it every work 100%
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
No I never contacted water furnace. I figured they wouldn't be interested in talking to a homeowner about issues. I will try to contact them. The system was installed in 2007 when we built the house. It has never worked properly since installed in my opinion. We have always had to use the electric backup to "help" the heat pump below 30 degrees. I'm not real sure how long the run times are supposed to be on these things. With there being no buffer tank it short cycles an awful lot. Especially in cooling.
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That's why I don't want to give up on it. I just need to find the right person and I'm striking out on that.
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But I can buy an awful lot of lp for the difference in cost between a boiler and geo hp.
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I don't know if those can modulate, but if it can, if it is short cycling that would suggest that fluid isn't moving somewhere. either that or the charge has escaped and it is cycling off on low suction pressure.
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I would say that absolutely the short cycling is your issue. The machine is trying to do its job and something is shutting it down. Any decent tech with a meter should be able to find that. Then there is the issue of can it be fixed with the install as it is.
If your WSHP is 3 1/2 tons which the model# looks like you need 10.5 gpm minimum on both sides of the unit. Call the well guy back and ask him if that is reasonable flow for what he installed. Is this a closed or open loop?
Water Furnace has a ton of info on their site. They have a lot of installers listed around Pittsburgh as well as the E-Mails of a bunch of territory managers you can contact.
Something could be piped wrong
It could be as simple as a dirty strainer
Wrong size pump etc.
I would also do or have done an accurate heat loss.
Could be shutting down on water temp, flow sensor pressure switch etc.
They also have drawing of how to install with a back up boiler and a buffer tank
Also your 16kw boiler has an output of 54720 btu.
Was this designed as a 100% back up for the heat pump or as a booster when the temp drops?
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A lot of times commissioning is not correct. Turn up the geo side pump speed if you can. Turn up all the pump speeds while you are at it for troubleshooting. The picture may not be representative, but I see many valves shut and a couple zones and pumps isolated.
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This heat pump cycles on temp. In heating mode it will run until it satisfies the set temp which i keep at 110 in the winter, then the unit will shut down and go into a 5 min delay before it will cycle again. It will continuously do this cycle regardless if there is a heat call or not. In cooling mode it will run to 50 degrees then shut off the go into an antishort cyclw for 5 min before it will kick back on even if there is still a cooling call. It will however not continuously cycle like it does in heating mode. It hasn't run all day today since the weather is cooler. So once this thing satisfies set water temperature it shuts down.
All the circulators are fixed speed including the geoflo circulator so there is no way to adjust as far as I know.
I had the valves closed in the pics for winter for the basement loops because it will get to 85 degrees down there because there are no check valves anywhere in the system. So anytime the system pump is running and the unit is heating water it is siphoning hot water to every zone regardless if its calling for heat or not. At least thats my opinion. If you grab the supply piping in the basement where a zone isn't calling or hasn't called the pipe will be hot.
This has always been an issue with our master bedroom which faces sw being way to hot in winter especially if the sun comes out for a little bit.
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It looks like it is 3.5 ton and single stage so it needs to move enough fluid on both sides to move that much heat.
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If you can reach anyone at WaterFurnace I'd give them that description and ask them if it should be running like that. You want to establish whether it's running as designed. If that's not normal, I would bet they'd have some idea of what might be causing it.
The issues of uneven heating don't really have anything to do with the heat pump, that's a sign of poor system design. Which is a hint that there might be other issues. Switching to a propane boiler wouldn't help with that.
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IF you do end up replacing, there’s no reason to switch with water furnace if you don’t want.
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Any HP pro you talk with will ask the same questions, what is the load, zoning, and what is the size and condition of the source water. So gather some data first.
Do you have a pond, loop field, or pump and dump from a well?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
It should be piped primary secondary and there should be flo checks in the circulators or separate flo checks for the zones. It looks like it is just pumping in to the manifolds so it might not get enough flow through the hx in the heat pump. It may be blowing past the flo checks because the circulators aren't isolated.
what are the return water temps out of the loops and to the heat pump?
does it short cycle if you open the closed zones?
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There are 3 vertical wells.
The entering temps from the loops vary. Normally 35 in winter and 72 or ao in summer.
Depending on the outdoor temps and load on the heat pump it will short cycle with all zones open.
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what are the temps on the supply and return of the load loops?
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"The entering temps from the loops vary. Normally 35 in winter and 72 or so in summer."
To me that's a severe red flag that the well is insufficient, or something is wrong with the way it's piped. If the well water is only 35F in winter there's almost no heat available before the water freezes. In Pennsylvania I'd expect the year-round ground temperature to be in the low 50's and the well water should stay at that temperature if the wells are property configured.
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How deep are the wells? 37° is way too big a swing in incoming temperature.
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180 feet
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Last time i checked there was a 7-8 degree delta t between supply and return through the well side
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you could have something as simple as an air locked loop in one of the wells.
Are there flowmeters on each well loop?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
"The entering temps from the loops vary. Normally 35 in winter and 72 or so in summer."
Those would be excellent numbers for the water coming off the heat pump and being returned to the wells. I want to make sure you've got the measurement straight.
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All the well loops are manifolded together in the yard. There is only 1 supply and 1 return coming into the house.
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Its hard to get a good temp reading especially in the summer because the run times are so short
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This winter i checked and was getting an 8 degree delta t and 2 psi pressure drop on the well side of the heat pump. I did not however check the supply and return temp delta or pressure drop on the load side at that same time. But I think I may yave found a geo guy that is supposed to be very knowledgeable come out and do some testing on the system.
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I could not find any p/t ports on the load side to make that happen.
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