I am guilty as charged....we didn't do any tightening before hopping on the GSHP bus. Better late than never, though, right? I've made the initial contact with an insulation company, and am looking at radiator valves. Should I be looking for something like the Honeywell BraukmanN?

outdoor reset ...you need to set it up higher temp than just to hold the house temp

That's one argument for using a heat pump plumbed in series with a single zone system. No outdoor reset needed and no need to pick a higher temperature (ie, reduce efficiency). Plus the HP always sees the coldest water available (further increases efficiency). If you do need outdoor reset, it would be nice if it self-learned and adjusted the needed temperature instead of using a fixed table.

We have seen over and over that typical Manual Js aren't very accurate. I would trust actual data from the house (heating bills and/or a few overnight measurements) much more.

Posted By jonr on 19 Apr 2013 10:08 AM

outdoor reset ...you need to set it up higher temp than just to hold the house temp

That's one argument for using a heat pump plumbed in series with a single zone system. No outdoor reset needed and no need to pick a higher temperature (ie, reduce efficiency). Plus the HP always sees the coldest water available (further increases efficiency). If you do need outdoor reset, it would be nice if it self-learned and adjusted the needed temperature instead of using a fixed table.

We have seen over and over that typical Manual Js aren't very accurate. I would trust actual data from the house (heating bills and/or measurements) much more.

If plumbed in series with a single zone, usually it is very uncomfortable. It takes way to long to heat up all the water with a geosystem sized to maintain the temp, but people here forget that sometimes you also also have to increase the temp. That is why a w-w design is tricky, and more than 100% load capacity is needed to make it work well.
Yes, can't wait for smarter outdoor resets. They are planning to make them communicating, at least one step in the right direction.

Posted By tamar on 19 Apr 2013 09:52 AM
I am guilty as charged....we didn't do any tightening before hopping on the GSHP bus. Better late than never, though, right? I've made the initial contact with an insulation company, and am looking at radiator valves. Should I be looking for something like the Honeywell BraukmanN?

Don't use the Honeywell. They can make a high pitch sound when they are only partially open or modulating. Danfoss valves work without issues. It is important to install them horizontally, not vertically like in the picture I sent you. You can also use the remote actuator with the wire.

doc- Try emphasizing the air sealing even MORE than the insulation. Insulating without air sealing often leads to mold, paint failures, sometimes rot problems from air-transported moisture accumulating in now-colder exterior wood. Without the air sealing there is still a high degree of wind speed uncertainty on heat load. Air sealing usually buys down more heat load per dollar than insulation too, but they rightly should be done in tandem (or rapid sequence- air seal first, then insulate.)

In my theoretical almost academic world I've manage to deal with any number of not-so-theoretical or academic houses and hit the numbers pretty close, including my in-laws' early 19th century antique that has a large ADDITION that is more than 100 years old, with dramatically different framing styles/types between the two parts. Infra-red cams & blower doors are really not that hard to figure out, no rocket science degrees required, and can unearth an unbelievable amount of thermal bypass issues (most of which are fixable once you know they're there) in these hard-to-figure antiques.

My in-laws kept their crummy but functioning low-efficiency heating system, put about 20-25 grand into the building envelope, reducing heating fuel use by over 35%. Higher efficiency heating would have cost more up front might have matched the fuel savings, but not the comfort. When they heating system dies they can replace with something better. (It's easier to make the financial argument for the higher efficiency heating if you're looking at displacing oil or propane rather than natural gas, to be sure.)

Linear modeling on fuel use against mid-winter HDD hits with high precision too, if you're consistent with the model and don't have too many errors to stack up & estimate (like how many cords of wood vs. gallons of oil, and "Oh yeah forgot to tell you, we spent most of January in Belize." etc.) Being even 5F off on the true balance point temp yields only a single-digit percentage error at design temp, if you're consistent with where the zero is for calculating both the slope & load.

Yes, there people get enamored of a technology (and subsidy) and won't be convinced that any part of the solution is in the building envelope, so no. I'm not advocating turning down work for not listening to your counsel. Simply not trying to disabuse them of that thinking isn't doing them any favors, and sometimes infra-red imaging of the otherwise invisible gaping holes in the thermal envelope can be the game-changer.

Not all my relatives take my advice any better than your customers. I still have two sets of in-laws heating with $4+ oil, and two others heating with electric baseboards & 15-18cent electricity. You can't push a string, even when the solutions are dead obvious, affordable, and dangled in front of them. (One of the baseboard guys is a geo-fan too, with a prime back yard & shallow water table for avoiding the granite drilling costs. Says he can't afford the geo. But his loads and layout are also amenable to ductless solutions too, yet he just can't quite get there somehow. I've been working on him for about 6 years & something like 40 grand in accumulated heating bills over that period, go figure!? :-) )

To get 40% more heat out by cranking the temp up, dropping 85% of the 120F efficiency requires significantly more system somewhere, if it's not the radiation. (I know, it's purely theoretical, kinda like the second law of thermodynamics, or gravity. ) Reducing 40% of the peak load to only a 5% wind-wash adder simply takes less mechanical system, no matter what temp & efficiency (or margin) you're designing for.

I still have two sets of in-laws heating with $4+ oil, and two others heating with electric baseboards & 15-18cent electricity.

I'm a bad person for chuckling at that.

Another situation you may feel free to chuckle at - My mom continues to burn $4 oil, and natural gas is on the road less than 200' from the house. I don't know what it will take to get NG to the house owing to rocky terrain, but I sure wish she'd get some estimates.

Posted By engineer on 20 Apr 2013 09:20 AM
Another situation you may feel free to chuckle at - ...wish she'd get some estimates.

Could she get an Engineer's estimate⸮

Posted By docjenser on 13 Apr 2013 12:14 PM
Your loopfield is not OK. While he calculates the larger of the 2 heatpumps needing 15 gpm (5 tons x 3 gpm/ton) he neglected that the header pipe and the loopfield should be designed for 24 gpm when both heatpumps are running. The Reynolds numbers are not the issue here, but him needing to push 24 GPM to and back from the loopfield through 200 ft of 1.25 is the issue. His calculations show that he calculated the header pipe and the loopfild only with 15 gpm, not the 24 nominally needed for 2 heatpumps.


The absolute killer is also the 10 ft of 1" pipe which sees the entire system flow of 24 gpm.

Even if you take the flow down to 19 gpm, which is considered the minimum (not the optimal), (2) 26-99 can only do 17 gpm under this design. He should have done those calcs before he put the pipes in, not after the fact. Although I am not sure here if he tries to run calcs now which fit his current design, of if he just does not know better.



Another issue is the control setup. Don't you want the radiant heat going first, and only when it is not enough the 2nd stage (forced air) comes on?


Both the control strategy, equipment selection and the loopfield design renders the geosystem inefficient. Especially when he keep adding pumps to overcome the inefficient flow design. The loops in the ground are OK, but you should add re-piping the header pipe to the boreholes to the list here. You need a 2" pipe here, also 2" pipe inside which see the whole system flow.
You are at the point where you need to rip everything out inside, exchange the header pipe outside, and redesign the system.

You (he) could put a 5 ton w-w in, and use the high temp as a second stage. Keep the Split for AC or as a 3rd stage.
Every one is up in arms here about popping in a 7 ton high temp WF, but this might be the cheapest options here. One single heatpump conditioning a buffer tank with an outdoor reset would do it all. Very simple.

Sorry to bring the conversation back several steps, but I have a question about the outside supply and return piping. This piping runs UNDER our house and comes up in the middle of the basement floor. I have no idea how something like this would be replaced. If the 1.25 in pipe is a limiting factor, does that take the 7 ton Waterfurnace off the table? As you might be able to tell, I am still considerig all options.

At our house, for the GSHP 'Outside' piping running into the basement, we made a chase at the baseboard level and piped through that. (2" and 18gpm @ 5psi+- ; 4t)

Posted By tamar on 20 Apr 2013 12:04 PM

Posted By docjenser on 13 Apr 2013 12:14 PM
Your loopfield is not OK. While he calculates the larger of the 2 heatpumps needing 15 gpm (5 tons x 3 gpm/ton) he neglected that the header pipe and the loopfield should be designed for 24 gpm when both heatpumps are running. The Reynolds numbers are not the issue here, but him needing to push 24 GPM to and back from the loopfield through 200 ft of 1.25 is the issue. His calculations show that he calculated the header pipe and the loopfild only with 15 gpm, not the 24 nominally needed for 2 heatpumps.


The absolute killer is also the 10 ft of 1" pipe which sees the entire system flow of 24 gpm.

Even if you take the flow down to 19 gpm, which is considered the minimum (not the optimal), (2) 26-99 can only do 17 gpm under this design. He should have done those calcs before he put the pipes in, not after the fact. Although I am not sure here if he tries to run calcs now which fit his current design, of if he just does not know better.



Another issue is the control setup. Don't you want the radiant heat going first, and only when it is not enough the 2nd stage (forced air) comes on?


Both the control strategy, equipment selection and the loopfield design renders the geosystem inefficient. Especially when he keep adding pumps to overcome the inefficient flow design. The loops in the ground are OK, but you should add re-piping the header pipe to the boreholes to the list here. You need a 2" pipe here, also 2" pipe inside which see the whole system flow.
You are at the point where you need to rip everything out inside, exchange the header pipe outside, and redesign the system.

You (he) could put a 5 ton w-w in, and use the high temp as a second stage. Keep the Split for AC or as a 3rd stage.
Every one is up in arms here about popping in a 7 ton high temp WF, but this might be the cheapest options here. One single heatpump conditioning a buffer tank with an outdoor reset would do it all. Very simple.

Sorry to bring the conversation back several steps, but I have a question about the outside supply and return piping. This piping runs UNDER our house and comes up in the middle of the basement floor. I have no idea how something like this would be replaced. If the 1.25 in pipe is a limiting factor, does that take the 7 ton Waterfurnace off the table? As you might be able to tell, I am still considerig all options.

Not ideal, but doable. The 7-ton waterfurnace has a different heat exchanger in it, with about 100 small channels, so water going through will have lesser friction loss. It needs between 20 and 25 gallon per minute. You would need another pump, replacing the (3) lesser efficient ones you have now (technically all 3 in series like you have right now could actually feed the 7-ton), but this will reflect in higher operating costs, what is part of what you experience.

The GV06 would probably do it: http://phoenixflowcenters.com/phoenixStore/index.php?cPath=53_37_55

More info is needed on the actual loopfield configuration, specifically the manifold configuration and length, the spacing between the tabs. Changing out the glycol and putting methanol in would also get you a few gpm more. The bottom line is that it is doable, but the devil is in the details.

Thanks, Doc. Will work on getting the loopfield configuration. All I know is that they drilled 6 wells. Would the 5-ton WF also require the GV06? Are there differences between the 5-ton and 7-ton other than size and price?

To make anything work for you in the 7-8 ton range, you need 20-25 gpm flow. Wether you combine a 5 ton (it does not matter if the existing split or a new w-w) with the existing 3 ton, your are at 8 tons x 3gpm = 24 tons. You could go down to 2.5 gpm/ton, but that is minimum.

The 7-ton has (2) 3.5 ton compressors, and uses a novel heatexchanger and design (including an other refrigerant) to get your supply temperatures up to 150F, specially designed for baseboard or low efficiency radiators. The 5-ton can only get up to 130F supply temperature.


My cast iron radiators need 135F supply temp on the coldest days here in Buffalo (+2F), NY, but Minnesota is a different beast. I don't know the specifics of your house. So to get the supplies temp and the amount of BTUs your radiators/your house probably needs you could either use a normal 5 ton and the 3 ton high temp in series without a buffer tank, but that would be a very complex control scenario.

The second option is to have your 3 ton provide your baseload, although not at high temps, and then have the boiler kick in, both feeding a buffer tank. And then at the coldest days (highest water supply temperatures) have the high temp shut off and only have the boiler do the load. Also some specific control strategies. Probably the best option to play with the cards you got. This is with an outdoor reset control and buffer tank.


Or you can just put in a 7 ton high temp with an outdoor reset and a buffer tank. Most here thinks it is out of the question, but if I were your contractor and have to make good on this, and count labor, materials and complexity of the design together, this might be one of the cheaper upfront options and serving you better in the long run.

Thanks Doc! If I want to get a local CGD involved, there are only 2 in the Twin Cities area. Will all CGDs have knowledge of hydronic design?

Posted By tamar on 21 Apr 2013 10:00 PM
Thanks Doc! If I want to get a local CDG involved, there are only 2 in the Twin Cities area. Will all CDGs have knowledge of hydronic design?

CGDs usually design loopfields, and geo systems. They may or may not know hydronics and radiant heat. Engineer, radiant heat contractor, Architect, many trades might or might not have knowledge.

It sounds like the RIGHT CGD might be hard to come by. If you ever decide to move back to MN, Doc, let me know. If you come back today you'll be in time for the 6-10 inches of snow they're predicting for this evening.....

Posted By Dana1 on 18 Apr 2013 06:34 PM
Staring at a 150 year old wall and taking a WAG at it's construction for a U-factor is never going to cut it, but shooting in the dark just isn't necessary anymore. I'm a believer in infra-red imaging under blower-door test to ferret out (and fix) any egregious insulation gaps & air leaks before embarking on anything as serious as specifying GSHP system (or even a low-temp mod-con boiler based system), at which point the heat load calculation error-window narrows considerably, and the deletory effects of wind-washing are much diminished, and the need for building in "just in case" margin melts along with it. Maybe that's not the geo designer's job (or maybe it is?), but it's pretty silly to drop that kind of coin with such huge error bars on the fundamental load numbers. Several grand up front nailing down (and lowering) the heat load is going to be money well spent, and more than likely largely offset on the back side in downsized mechanical systems and operating cost, with a real up side on comfort worth paying for even if the mechanicals stayed the same.

Running a GSHP without outdoor reset control on a hydronic output system in a climate like MN seems like a fundamental error on the original system designer's part too, but that's probably not a very expensive fix. Outdoor temperatures don't track the increase in load with wind at ALL, and if you're leaky enough to be suffering docjenser's stated 40% increase in actual load in a wind vs. no-wind situation, you'd still have to run water temps much higher than optimal to cover that potential. A 40% hit with 40mph wind would have to be a MIGHTY leaky house though (yet I'm sure they exist- I've lived in one of those).

My bottom line is that it's always going to be better to start with a tight house, and the notion that you can't get there with a classic Victorian is just plain wrong. It isn't always super-easy or super cheap- it might take 3 guys 3 days to really tame the beast whereas in a simpler-newer house it can be a 1 day 2 guy sort of deal. But even a week's worth of air sealing & spot insulation would usually cheaper than a 40% overdesign on the GSHP to be able handle wind factors on the coldest night of the decade, and it's a bigger upgrade in comfort all the time than any heating system is capable of delivering.

Tight is right- always. I like Curt Kinder's theatrical smoke & blower door pressurization approach to making sure his foam contractors don't leave the job site with gaping holes remaining on attic sealing & insulation jobs as part of his take on geo designs. I wish more GSHP contractors had a more whole-systems approach, taking a truly serious stab at the envelope deficiencies as part of the process, not just the dead-obvious, lowest hanging fruit. High efficiency heating systems don't deliver comfort, higher efficiency buildings do.

---------------end of soap box speech------------------------------ (at least for now. ;-) )

I just had a visit from an insulation contractor, and he said all house is already very tight. All the insulating work seems to have been done by previous owners (except for replacing windows). He did not use infra red, but was able to see where the attic has had insulation blown in via the kneewalls, and also where the basement has been foamed around pipes and the basement ceiling insulated. The search for lower energy bills continues.

Sometimes you have to play with the cards you have. That is the price you and me pay for living in an older charismatic home.

> I just had a visit from an insulation contractor, and he said all house is already very tight.

If he didn't do an actual test, his assessment isn't likely to be very accurate.

Posted By jonr on 01 May 2013 07:07 PM
> I just had a visit from an insulation contractor, and he said all house is already very tight.

If he didn't do an actual test, his assessment isn't likely to be very accurate.

Nobody, (and I mean NOBODY) can walk into a house, poke around at the insulation and declare it "tight".  It's a relative term, and while one could easily state that it's "tighter than some shack with no wall insulation" with a visual inspection, without pressurizing/depressurizing and measuring the air flow you really can't tell how tight it is. Curt Kinder's ("engineer") foam installers converting attics into conditioned space are dedicated & competent insulation installers, but he still doesn't let them break down before doing the house pressurization & theatrical smoke test to find & fix the other 3 square feet of air leakage that was hard to see & fill on the first pass.  The problem with air leakage is that it's really sneaky, it doesn't take much to hide quite a cross-section of leak.

The framing complexity of multi-story Victorians have a great number of possibilities for gaps in the insulation and thermal bypass air channels, which much easier to find in pressurization/depressurization testing in combination with infra-red imaging.  If the house tests under 1000cfm/50 without the IR imaging, fine, it's not going to have excessive natural air leakage, but it could still have significant gaps in the insulation.

I suspect the contractor declaring it "tight" didn't have the requisite air sealing & testing equipment or experience, and saw that it was already had substantial retrofit insulation, making it a low-volume low-profit job for the services they actually DO provide.