WaterFurnace Series 7 – Total Cost Breakdown

[Supervstech]

The lesson learned was how to manufacture units that last just past warranty end!

Oh yeah...
Commercial equipment only has a 90 day, to 1 year warranty, and a lot of companies had to shell out mega bucks replacing 2 year old corroded coils...

Trane replacement evaporator coil was 7800 cost, on a 15 ton unit that cost 8200 to replace entire unit...
Total robbery.

 

[AlyGreen]

AlyGreen, Awesome writeup. As you pointed out in a previous post, there are air and water combo units. I put in a Synergy 3D unit by waterfurnace (4 ton).

Works great for this house because it occasionally gets all the way down to -40 here. I use it for hydronic heat, domestic hot water assist, and air heat.

One item I didn't see on the awesome writeup was to isolate the vent system from vibration too if putting in a new unit. Relatively easy with some fanfold looking rubber as a small section of duct.

I have been on it since 2010. The pre-biden prices were pretty decent. 30k before rebates, and just over 20k after. It actually came out to match exactly a forced air system after rebate, and included in the 30k was a nice propane fireplace as a backup.

Not perfect. I have had a compressor replaced under warranty, but other than that, coming up on 14 years, and I would do it again, depending on the price. The calculation changes where air source heat pumps have enough heat to work with.

@SunDave Your temperatures are way lower than ours. Not sure if that was celcius -40C or farenheight -40F. I agree that once the air temperatures have dropped that low, you are likely almost completely running on a supplemental heat source, even with the best air source heat pumps today. Our previous house and air source unit had a defrost cycle in winter low temperatures. When the defrost cycle was running it kicked on electric coil supplemental heat that pulled a lot of energy kWh.

Ground Source
I do like the ground source system more for having a constant ground loop temperature to work with for heating and cooling. This makes it independent of the outside air temperatures for its ability to heat and cool the house efficiently. At those lower temperatures, how good the home's insulation is, is the greater determinant of how hard the system has to run to make up the heat loss.

Basement Insulation
Our home was rebuilt in 2015 by the previous owners, on top of the existing 1970's basement. The home has adequate but not great insulation. One future project of mine is ideally to curtain insulate the 8 foot high basement walls to drop 13,000 BTUs off the load. We could not isolate the basement air exchange from the rest of the house. At least our installer did not recommend doing so, due to the unfinished nature of the older basement.

I am thinking curtain insulation over a second wall with ridgid foam board, due to non-existant exterior basement wall waterproofing. The walls need moisture exchange, a tough problem to get around without alot of expense. I am undecided whether to do this or if it will cause me more problems with mold than it is worth the heat savings from dropping 13,000 BTUs off the house load.

Vent System Vibration
When you say to isolate the vent system, are you talking about a totally air sealed home that has a fresh air intake from outside (vents) and a heat exchanger swapping inside air with outside air? Our home is too air leaky to need such a system but I can see how a vent might need isolating. If not this then what vent do you mean please?

Ground Loop Seals
We just have the ground loops going through the basement foundation wall and they use rubber gasket seals outside and inside the wall but no vibration damping. The amount of vibration conducted via these pipes once they penetrate the concrete foundation is minimal. Most of the vibration issues we had was transfer to the floor/ceiling joists above.

The sobothane bushings on the U clamps took nearly all of that away but not totally. The reduction was good enough for what I needed to avoid going even more heavy duty on the isolators.

 

[SunDave]

Vent System Vibration
When you say to isolate the vent system, are you talking about a totally air sealed home that has a fresh air intake from outside (vents) and a heat exchanger swapping inside air with outside air? Our home is too air leaky to need such a system but I can see how a vent might need isolating. If not this then what vent do you mean please?

Hi AlyGreen,
I have this type of connection in the heat side, and cold air return of the ducting. It allows the furnace to be connected to all the ducting, but without a rigid metal to metal connection. Other than this, the geothermal unit sits on cork and rubber pads on all 4 corners to reduce vibration. It's on a concrete floor, so that doesn't move much.



Interestingly at -40, both Fahrenheit and Celsius are the same.

I went with a closed loop, at about 10 ft depth ( a horizontal loop). I had a friend that does excavation so we made it nice. I put in about 3600 ft of loop field tubing plus some for the header. If I recall correctly, it is (4) 900ft loops of 3/4 inch tubing, then the header is about 1 1/2 inch. If I were to do that again, I would definitely have the header in the house vs burying it, although it has not yet caused problems.

I learned how to service almost everything myself over the years.

I have strip heaters in the unit, but have never needed them, even on the coldest of stretches, so I guess we insulated well.

Glad to see the ground source route is working out for you as well. It may not be the cheapest option, but it is a really solid option.

Good advice on the placement and noise factor too. These units are not silent, not super loud though either. I put mine in a room near the garage, but that room also has exterior doors and seals, even though it is an interior room. That definitely works to pretty much eliminate the noise. You would never hear it over the very faint vent air noise.

 

[Supervstech]

I was just going to post that -40 is the crossover point between F and C...
Below that C is colder than F... but AT -40, they are the same.

 

[AlyGreen]

@SunDave What a great flexible plenum to ductwork connection, thank you.

When we redo the ductwork I will ask the installer to add a similar flex connection into the system at the plenum. I think these flex connections both help with vibration suppression and help reduce sound transmission through the ductwork.

Ductboard v Metal v Flexiduct
When redoing our ductwork, I have been debating ductboard over metal. The ductboard will be a preinsulated all-in-one product so there is no need to thermally insulate along the outgoing heat duct and/or the cold return duct if you are being really careful. Certainly it is a cheaper product. However more importantly to me, the ductboard may better absorb sound but am not 100% sure about this, does anyone have knowledge or experience about this in the forum? Certainly there will not be any metal expansion and contraction sounds with the ductboard.

Reading up on ductwork sound transmission mitigation, people were recommending adding the flexible connection you have at the plenum, plus some curved flexiduct just before the registers & returns, as being a good way of absorbing and stopping sound transmission through the ductwork.

Who knew sound and vibration could be such a challenge? All we want is the quiet sound of air movement but it takes some careful engineering and good installation.

 

[Partimewages]

Flex connections at the unit supply and return like @SunDave shows.
We always hard piped everything in the system except for the last 5-10' to the register boot. Small length of flex to kill noise.
The flex connections knock the noise of the equipment out. Flex at the end of the run helps air noise.
NOTE most noise comes from a poor duct design. Trying to push to much air through the duct creates most of the noise in the system.
We used some duct board but rarely do we recommend it anymore. If you need to insulate use internally lined metal.
All of this comes from 40 years of experience in the industry.
Remember cheap = noise. The cheapest contractor cannot mitigate noise for their price!

 

[Supervstech]

@SunDave What a great flexible plenum to ductwork connection, thank you.

When we redo the ductwork I will ask the installer to add a similar flex connection into the system at the plenum. I think these flex connections both help with vibration suppression and help reduce sound transmission through the ductwork.

Ductboard v Metal v Flexiduct
When redoing our ductwork, I have been debating ductboard over metal. The ductboard will be a preinsulated all-in-one product so there is no need to thermally insulate along the outgoing heat duct and/or the cold return duct if you are being really careful. Certainly it is a cheaper product. However more importantly to me, the ductboard may better absorb sound but am not 100% sure about this, does anyone have knowledge or experience about this in the forum? Certainly there will not be any metal expansion and contraction sounds with the ductboard.

Reading up on ductwork sound transmission mitigation, people were recommending adding the flexible connection you have at the plenum, plus some curved flexiduct just before the registers & returns, as being a good way of absorbing and stopping sound transmission through the ductwork.

Who knew sound and vibration could be such a challenge? All we want is the quiet sound of air movement but it takes some careful engineering and good installation.

I despise ductboard.
I always install metal ductwork, and i line the trunks with 2" fiberglass liner internally.
Absorbs all sounds, and fully insulates the ducts.
If the ducts are in conditioned space you can use 1/2" liner, strictly for sound mitigation.

 

[AlyGreen]

@Partimewages & @Supervstech Thanks for the clear information and experience behind the preference, much appreciated.

 

[AlyGreen]

There is an interesting issue with decreased ground loop pressurization and increased vibration with our system.

I found that when the pressure in the ground loops is lower than recommended specification, then vibration amplitude can increase in the ground loop pipes. The standard pressure for our pipe length is 50lbs and as it drops over time, vibration or the shaking of the pipes, can increase. When put back to 50lbs the amplitude of the pipe vibration decreases, they shake less.

To put this in perspective, these are minor, not massive vibrations but the frequency of the oscillation reduces with the correct higher pressure applied in the ground loop. The speed of the ground loop pump also directly effects this. The higher the system load, the faster the pump goes, which is normal behavior.

So every six months I have the recommended maintenance where the coil is cleaned, the ground loop water pressure is checked and adjusted (repressurized) plus diagnostic readings are taken with the WaterFurnace Aurora AID Tool Kit . Repressurizing the pipes reduces vibration and looking into the physics of this phenomena, there are some complicated factors at play, really beyond my grasp, but here is a good article summarizing some of the possible causes.

https://www.sciencedirect.com/topics/engineering/piping-vibration

According to our geothermal installer, over time the closed ground loop pipes expand slightly, so need the pressure adjusted back up by a small injection of additional water. This is added via a supply valve and a small hand pump into the closed ground loop.

Just some more fun facts for people to consider. A properly pressurized ground loop will help the system exchange heat most efficiently.

 

[Partimewages]

Your ground loops are either expanding or contracting all the time. If you're in cooling season and rejecting heat they will expand and the system will decrease pressure. The opposite happens in heating mode.

 

[AlyGreen]

Your ground loops are either expanding or contracting all the time. If you're in cooling season and rejecting heat they will expand and the system will decrease pressure. The opposite happens in heating mode.

How geothermal works is really fascinating, thank you for that expansion/contraction insight. Half the fun of getting the system was doing the initial research then watching all the work in progress, drilling, install, commissioning, plus learning how things really work in practice. It is such an incredible heating/cooling technology.

 

[Partimewages]

Are you having a noise/vibration issue?

 

[AlyGreen]

Are you having a noise/vibration issue?

Mostly fixed now, I wrote about it in the initial post. The unit was initially installed on a concrete floor and directly on cinderblock (by my request to elevate the unit above occassional basement floods in really heavy rains) and the pipes screwed into the ceiling/floor joists with U clamps. Initially the vibrations were transfered up into the bedroom floor and we could feel it while lying in bed plus in the sheetrock walls. It was noisy as heck as well, my wife wouldn't sleep in the bedroom but moved to the couch.

So $3,076 dollars later I had a solution... couldn't live with it.

Used sorbothane bushings for the U clamps and an anti-vibration mat for the base of the unit. This majorly solved the vibration isolation and greatly helped with the sound reduction.

Before that I had first tried using Dynamat designed to lessen vibration in car bodies plus Dyna-Hoodliner sound deadening, designed to kill engine noise. I was trying anything I could think of, and learning as I went. Dynamat + Dyna-Hoodliner helped but what really helped more was the sorbothane bushings on the piping and anti-vibration mat for the unit itself.

Learnt that the compressor already had isolating springs and a sound jacket built-in with the Series 7 so nothing to do there.

For the unit ground mount, I had to find replacement blocks that were slightly lower than the original cinderblock to allow for the new matting on top. I found blocks giving a solution within an eigth of an inch of original unit height. So I used two car scissor jacks and a long block of wood to (very slightly) elevate and support the unit while swapping the blocks and placing the matting on top. Had to keep the same install height as the ground loop was attached to the floor/ceiling joists.

I am actually about to improve the sound box by adding a topper and some more rockwool, while still allowing air flow circulation for cooling. Things are pretty good, it was just an unfortunate location directly under the bedroom, we didn't know and had been assured the units are fairly quiet so did not anticipate any problems. The installer confirmed the shipping bolt had been correctly undone and loosened so it wasn't that.

Anyway, our problems are near completely fixed and we are happy. Just a slight resonance at heat 8 / fan 7 for some funky reason. When I did the sound analysis there was one measured frequency at 100Hz that was too low for the 8 inches of rockwool and half inch plywood to absorb so this isn't really a surprise.

 

[Partimewages]

Are you an audio engineer? Do you consider yourself/household to be more aggravated by noise?
Our geo installations always used:
Duct collars on supply and return.
J hooks around the pipe insulation for support.
Flex Duct at the end of each run.
Duct offsets to mitigate direct noise.
Rubber blocks under the equipment and behind the pump mounting.
Duct sizes that reduced th FPM through, for quiet air flow.
This is interesting because the equipment we used had the compressor in the air stream.
We would get calls from newly installed systems telling us they couldn't hear it run.

 

[AlyGreen]

Are you an audio engineer? Do you consider yourself/household to be more aggravated by noise?
Our geo installations always used:
Duct collars on supply and return.
J hooks around the pipe insulation for support.
Flex Duct at the end of each run.
Duct offsets to mitigate direct noise.
Rubber blocks under the equipment and behind the pump mounting.
Duct sizes that reduced th FPM through, for quiet air flow.
This is interesting because the equipment we used had the compressor in the air stream.
We would get calls from newly installed systems telling us they couldn't hear it run.

@Partimewages Not an audio engineer...just a man whose wife moved to the living room to sleep on the couch and knew he had to find a solution damn quick, having been the one to convinced her to go geothermal and spend a large sum of money. I felt deeply responsible and that it was definitely down to me to fix it. Its amazing what marital motivation will do for your ability to research a problem!

I good researcher willing to learn and fast.

Thanks for your install methodology information, really good to know. I am not an HVAC installer or expert, just a homeowner. We hope for the same quiet result as you got once our ductwork is redone, as the last problem was a roaring sound in the returns in the bedroom ducts, which also disturbed our sleep. When you retrofit into an old oil burner + ductwork situation, know that the air speed may increase in the existing ductwork was the lesson.

For anyone reading this, we love our WaterFurnace Series 7, it is some seriously awesome kit, we just had a few initial problems and I don't want to discourage anyone from going this route. One of the reasons I wanted to share our experience, both cost and fixes was to help others. There was some but not a lot of noise remediation advice on the Internet about geothermal.

Yes to your question, I am hyper-sensitive to noise but wife is not so when she had a problem, I knew we had a problem.

 

[Partimewages]

Sorry to say but noise mitigation and HVAC don't go together well. Most HVAC contractors size things small to save on price. People in general tend to buy price over quality sadly. I tend to over engineer things which never helps low price. Don't hesitate to reach out, I'll help if I can.

 

[AlyGreen]

Sorry to say but noise mitigation and HVAC don't go together well. Most HVAC contractors size things small to save on price. People in general tend to buy price over quality sadly. I tend to over engineer things which never helps low price. Don't hesitate to reach out, I'll help if I can.

Thanks so much.

 

[SunDave]

AlyGreen,
I'm sure Partimewages is more experienced than I am, but I will add that I agree that the loop pressure can affect noise. For a while I had a similar issue of loop pressure decreasing often. With my luck, if figured it was worse case scenerio, meaning a leak in the loop field. Well, it turns out that the service people and I had been missing something obvious. There was some rust staining by the loop field pump pack, so that led to me just tightening a fitting, and it improved greatly. Now I am more eagle eyed when it comes to looking over equipment.

In the interim, I have learned to add pressure to the loop myself, so I have a transfer pump, some hoses and gear to do that myself now. If the loop field is good pressure wise, the thing is very quiet.

Same as Partimewages said, if you have a specific issue, I may have seen it, so feel free to ask.

 

[AlyGreen]

@SunDave I so appreciate the offers for help from you all.

For now I think we have the problem solved, as much as can be. Hoping the sound box topper will capture the last remaining little bit of hum that I hear. Partimewages pointed out a relevent fact, that I am hyper sensitive to noise, just born with accute hearing. For a regular person, where we are at now shouldn't be an issue.

The wife moved back into the bedroom a long time ago after the fixes put in place so all is well that ends well.

I respect your ability to maintain your own geothermal system, that takes some expert knowledge.

 

[AlyGreen]

Just some more data, direct from our electricity supplier MetEd, PA.

Barcharts showing total household electricity usage, including heat pump for 2023.

For a breakdown of just heat pump usage, and heat pump as a percentage of the total kWh, please look at the spreadsheet referenced in the first post of this thread. Look to the bottom right hand spreadsheet corner to see year-on-year 2021-22, 2022-23, 2023-24 in table format.

2023 - Monthly Usage + Air Temperature Barchart



2023 - Daily Usage Ave in Chart Form