Missouri Which Flow Center for new system

I'm in St. Louis, Missouri and will be converting my existing Propane Furnace and A/C unit to Geothermal. I've received several quotes that I'm happy with. I think I would like to go with the GeoComfort Navigator 4 ton (GYT048) with probably 3 x 200ft vertical loops drilled by geothermal subcontractor for my home. My quote is for a little over $20k (before tax credits) and I provide the electrical drops and a spare water storage tank for desuperheating. I will also install or have installed a tankless propane water heater feeding from the storage tank. I asked how he determined 4ton and he stated based on the number of systems he installed similar to my home and in his own home. He said he can do the load calculations if I like.

I've seen several questions after reading threads on here.
1. Any issues with the above?
2. The proposed Flow Center is quoted as mod#GeoFLow AGFC2. Is this a pressurized system with 2 pumps and should I be requesting a more efficient pump?
3. If I purchased the tankless system myself at this same time, Can I submit this with my claim for the tax credits or would I need to have the HVAC guy sub-k it and put it on the same bill to ensure tax credits approval?

 

Off hand, it looks like you have 3 tons of loop and 4 tons of unit. That would be fine if you only have 3 tons of load. But if you only have 3 tons of load, why purchase a 4 ton unit?

What type and size of loop pipe is being proposed? What type of grout for the well?

With respect to the flow center, what make and model pump is proposed? For the amount of pipe being proposed unless the wells are hundreds of feet from the home, a single Grundfos 26-99 3-speed pump should be sufficient and very efficient.

 

Hi and welcome!
Get the load calculation done, then have another done by someone else. Without data you are making a 20k guess.
Eric

 

Ok, I have 2 bids with load calcs and price quotes for my preferred brand with $5k difference in price for same 4 ton unit. Any thoughts on the extra loop and pumps?
My preference is 1 aux heat as supplement. If the furnace breaks, my wood stove insert heats my home nicely even at these cold temps we've been having here in Missouri (tested last week).

Proposed system:
4 ton unit 2 speed rated at 32,000 / 39,000 Btuh heating and 42,600 / 53,300 Btuh Cooling and using desuperheater into a buffer tank for hot water.

Option 1:
Annual Heating Load est: 67.7 MMBtu Ann. Cooling Load est: 54.0 MMBtu
Design Heating Load: 64567 Btu/hr Dsg. Cooling Load 47182 Btu/hr
Pressurized Flow Center, 2 pumps, UP26-116, est: $164/yr
Loop: 5ea 150ft bore depth using 3/4" pipes run well to furnace probably 40-60ft. (rep states this is 5 tons of loop)
2ea 10kw aux heater installed

Option 2:
Annual Heating Load est: 62.9 MMBtu Ann. Cooling Load 45.8 MMBtu
Design Heating Load: 60,000 Btu/hr Dsg. Cooling Load 40,000 Btu/hr
Non-Pressurized Flow Center, 1 pump, UP26-116, est: $86/yr
Loop: 4ea 150ft bore depth using 3/4" pipes run well to furnace probably 40-60ft.
1ea 10kw aux heater installed


My thoughts for hot water are either a 199,000 BTU tankless propane (aquastat added to adjust for variable desuperheated water temps) or an air source heat pump 80 gallon hot water heater (prob Rheem). I'm leaning towards the HP to get off of propane our propane supplier is very high ($3.29/gal-$3.99/gal plus taxes and multiple fees). I have a 500gallon buried tank that they also charge me $100/yr for leasing.

 

I asked one of my potential contractors about using a variable speed loop pump (blower and compressor are 2 speed/stage). He thought it wasn't worth it, but offered to install a variable pump for an extra $1075. That would be a 15 year payoff if using the estimated electricity savings. And more expensive(??) to replace if it breaks in less than 15 years....

quoted: "The loop pump is not 2 stage. A 4 ton unit doesn’t justify a 2 stage pump. If you would like a variable speed pump we can install one. It will be a Magna 32-140. I’m not sure it’s worth the extra $1075. I have attached an energy analysis that shows the savings of it."

I've read a lot of discussions on here about savings with loop pumps. Did the above discussion miss any points I should be considering?

 

They both mention the UP26-116 pumps, DocJenser always says those are inefficient pumps, better to use the 26-99.

I like my heat pump hot water heater.

 

Second on the scrap the 26-116 in favor of the 26-99. I could not justify the variable speed upcharge for your proposed system.
Eric

 

The variable speed circulator pump is the best solution, but pricey.

It takes some skills to fine tune it so it operates at the right speed for the perfect flow for the heat pump at different stages. An it takes the right control mechanism to dial in and turn on the right speed of the pump.

We use them as standard now.

Attached is an example of a dual stage WF operating at 1st stage. Blower is turned down to use 103 watts, circulator pump uses 51 watts.

Compare that to (2) 26-116 using 2 x 380 watts = 760 watts when running.

A single 26-99 would use 230 watts when running at the highest stage. I don't get it why one would put in a 26-116, when a 26-99 would do the job. And in view of that, why would you put in (2) 26-116?

It would raise a flag about the skills of the installer to understand on how to build you an efficient system.

 

Wow, thanks docjenser!! Very impressive skills and experience.!

Is this something that takes additional sensors that only come on a WF7 (I thought I’ve seen that you normally order your systems with optional boards that include extra sensors) or do all brands units have these sensors? Or do have tools/equipment that you connect to test these various points in the system to set it up once at install?

Does a pressurized flow center require 2 pumps? At least that’s my guess as a new to geo homeowner.

 

No.

 

Yes, WF makes it very easy since the monitoring can be ordered as an integrated accessory for the dual stage 5 series and the variable stage 7 series, and now also for the regular water-water units. We get them with every one of our installs.

 

Quote 2 was also for a pressurized flow center with 1 pump. He says he can put in the 26-99 pump and it should suffice.
I asked how much to add a non-pressurized flow center with the NP or NP+ series and he said it would add $300.
He said he's been installing GeoThermal since 95 and has always installed pressurized systems. They ensure they do a really good job of removing all the air from system to prevent flat loop callbacks. I've been researching the non-pressurized NP from GeoComfort. This seems like a good thing long term with easier servicing if required. Should I go with non-pressurized?

 

ChrisJ, could you post (or have you already) pics of your setup with Geothermal furnace, buffer storage tank, and air-source heat pump hot water?
I saw your statement that is only 2-3* difference in the ambient room temps. That's encouraging.

I asked the price to add a dedicated Hi-Temp GeoThermal Hot water pump (additional unit, not desuperheater) and that was an additional ~$6000 after tax credits.

The air-source heat pump hot water is about $1500 plus install costs. I think I'll be eligible for a $500 refund from my electric company.

 

Flyboy. I've got a presseurized system that is doing great now, but there were a couple times I had to add fluid to loops. I'd have much preferred a NP system for minimization of stanby leak potential as well as ease of maintenance when required.

 

I don't have any good pictures, I will take some tonight. The pipes connecting the heat pump to the storage tank go around a corner and over the doorway.

There is a lot of copper piping in the 2 pictures I do have.

 

Thanks for your replies!! I'm going to have them make it non-pressurized with an NP storage tank and a 26-99 loop pump set to single stage. If I get advanced in my journey, perhaps I can look into adding 2 stage to the loop pump later, maybe even DIY.

I'm scheduled/queued and waiting for the driller to start drilling. I'm going to do the trenching under the deck to save some manual labor from the driller to where the excavator can't reach and to come in at my preferred location. I'll rent a small trencher for my piece from Home Depot.
They use pre-pressurized lengths of 150, 175, 200, or 300ft of 3/4" and maintain equal lengths in the field. Then larger pipe coming into the house.

Another design decision question, the quote is for 3 x 200 ft wells, which is 300ft of loop per ton in the ground-1200 ft of line total, per the manufacturer.
I asked how much for an additional 200' well, and was quoted $1500 per 200' hole. Should I add another loop given others suggestion that more is always better, but at reducing cost effectiveness. I figure this is the only time I'll make this decision since the headers will be buried outside.

Any thoughts from this group on adding one more well?

 

Does the installer or driller have any data on average operating temps in your area using the 300' of loop per ton? The answer is in the data. In my area I added a extra loop to my 2 ton field and 3 ton field. That extra loop only netted a 2 degree improvement on loop temps vs. a conventional design.
Eric

 

Got the GeoAnalyst estimate back for (a) 3x200' vs (b) 4x200' wells: Option (b) costs $25/year more and $1827 more up front (extra well and extra pump)

a) est annual operating cost: $1035
average Heat Loop Temp: 49.1* Avg Cool Loop Temp: 68.9*

b) est annual operating cost: $1066
average Heat Loop Temp: 50.7* Avg Cool Loop Temp: 65.6*
-- extra loop length requires adding a 2nd UP26-99 pump, so running 2 loop pumps defeats the electric savings

Installer has the similar system to mine and his emergency heat never kicks on for his 4 ton system with 3x200' wells. He has aux heat breaker turned off so the house would get cold if it didn't keep up. But he also has water 100' down, so his loop is most likely wet and transfers heat easily. I'm not sure where my water table will be, I'm at the top of a hill.

 

That doesn't make any sense. If your installer told you this, I would question his knowledge about pumping water.

Whether you have 3 loops or 4 loops each at 200' deep, you still need to move the same volume of water which is dictated by your load / heat pump size. In this case with a 4 ton unit on a closed loop, you need ~3 gpm/ton or 12 gpm total. If you have 3 parallel loops, you are moving 4 gpm down each loop. If you have 4 parallel loops, you are moving 3 gpm down each loop. The 4 loops with 3 gpm flow down each loop is going to offer much lower flow resistance than the 3 loops with 4 gpm flow. So with 4 loops your are moving the same 12 gpm as with 3 loops, but with lower flow resistance. It is as simple as that. If anything, you would need LESS pumping power with 4 loops as compared to 3 loops assuming they have the same pipe length.

 

After re-reading my first post, I've decided to install a Rheem 65 gal Heat Pump water heater as opposed to propane tankless water heater. If I'm going strive for efficiency, why not go heat pump for both (just not geothermal for both) and really ditch propane. I'll probably keep the propane tank since I have a nice gas range and a propane generator.

I also opted to add the Sensi WiFi Thermostat and the Soft Start kit from the factory on my GeoComfort system. In case I add a whole home generator, the Soft Start will reduce surge requirements for generator sizing.