My impression is that they do coordinate the control of the fan coil blowers. But for sure, the pump is inside the box, and is variable speed, so I'm pretty sure coordinating at least that piece is part of the package they are selling.

Retrofit radiant floors seems like a good application for this--I'd be curious whether that turns out to work. I suppose it could be radiant floors at a lower temperature than would be necessary to supply the full design load, supplemented at a by a fan coil that does double duty in adding A/C in the summer. Or you could keep the oil fired here to use 10 (?)days/year when the higher temperature is needed.

Posted By Dana1 on 07 Oct 2015 02:14 PM
But I'll grant that can't easily get radiant floor heating out of a mini-split, ducted or otherwise! :-)

Cheap air source chillers (Chilltrix or others) aren't really suitable for the climate- most don't even have output ratings below +25F or so. That's fine in climate zone 3, or marine zone 4, but for zone 5/6 fuggedaboutdit.

Concentrate on the building envelope first, run the load numbers, and report back. With a fairly simple building shape and some careful decisions on window sizing/performance/placement you'd be able to hit Net Zero fairly easily following the whole-assembly R guidance in table 3 of in the BA-1005 document. With a Net-Zero-Capable building envelope the design heat load will come under 25,000 BTU/hr or even under 20,000 BTU/hr, making the HVAC systems cheaper and simpler to decide on.

Sorry guys, but a lot of this discussion is well over my head. Load numbers will be difficult. I am building a log home with raw un-milled logs. Because of this I am assuming that I won't have the most air-tight envelope although, many people who have built with this style talk about amazing thermal performance. This is partly due to thermal mass of the logs. I haven't been able to find any 'scientific' info on log walls for insulating purposes. The house will be 40x40 square, with an ICF walkout basement. 17' high walls and cathedral ceilings. The south facing wall will be loaded with windows and I am planning on 12" of EPS foam for the roof insulation. Using some basic calculators I have found online I need somewhere between 70-85k btu. Considering I am ONLY interested in radiant heating (ducts blow too much dust around in a log home, and due to the high ceilings, I want the ehat at the floor) - is the Chillix product mentioned here the best way to go? In terms of cost effective heating/ low utility bills for the next 50 years?

Posted By logbuilder7 on 10 Oct 2015 10:51 AM

Posted By Dana1 on 07 Oct 2015 02:14 PM
But I'll grant that can't easily get radiant floor heating out of a mini-split, ducted or otherwise! :-)

Cheap air source chillers (Chilltrix or others) aren't really suitable for the climate- most don't even have output ratings below +25F or so. That's fine in climate zone 3, or marine zone 4, but for zone 5/6 fuggedaboutdit.

Concentrate on the building envelope first, run the load numbers, and report back. With a fairly simple building shape and some careful decisions on window sizing/performance/placement you'd be able to hit Net Zero fairly easily following the whole-assembly R guidance in table 3 of in the BA-1005 document. With a Net-Zero-Capable building envelope the design heat load will come under 25,000 BTU/hr or even under 20,000 BTU/hr, making the HVAC systems cheaper and simpler to decide on.

Sorry guys, but a lot of this discussion is well over my head. Load numbers will be difficult. I am building a log home with raw un-milled logs. Because of this I am assuming that I won't have the most air-tight envelope although, many people who have built with this style talk about amazing thermal performance. This is partly due to thermal mass of the logs. I haven't been able to find any 'scientific' info on log walls for insulating purposes. The house will be 40x40 square, with an ICF walkout basement. 17' high walls and cathedral ceilings. The south facing wall will be loaded with windows and I am planning on 12" of EPS foam for the roof insulation. Using some basic calculators I have found online I need somewhere between 70-85k btu. Considering I am ONLY interested in radiant heating (ducts blow too much dust around in a log home, and due to the high ceilings, I want the ehat at the floor) - is the Chillix product mentioned here the best way to go? In terms of cost effective heating/ low utility bills for the next 50 years?

In your climate, with the capacity needed, you won't get there in a cost efficient way with air sourced heat pumps. You need a system which does not bow down when you need it the most, and with radiant, you need a bit of extra capacity to respond in a reasonable amount of time to the thermal inertia. In my book, with what you are describing, you need about 10 tons of system capacity, including hot water generating capacity. Upstate climate is not very different than Buffalo NY climate.
Most important thing will be your radiant floor design, and the load side of your system.

Posted By Dana1 on 08 Oct 2015 02:05 PM

Posted By chrs on 07 Oct 2015 03:46 PM
Dana, I can point you to the data Chiltrix has online, but I can't vouch for how accurate it is. Scroll down on this page to plots and data tables.

http://www.chiltrix.com/chiller-technology.html

docjenser: Yes, the source of defrost heat for mini-splits is indeed the indoor air.  During defrost mode they throttle back the blower speed to the minimum speed on the indoor head to limit the potential comfort problem.  I thought you had a Mitsubishi GExxNA at your house, and had observed it's behavior in defrost mode(?). Perhaps I'm remembering someone else complaining about how it was spending all it's time in defrost mode and never heating when it was +5F outdoors, which would be atypical for the FE or FH series units (not sure about the GE.)

No, that was me. The point was that it is taking BTUs from the conditioned space to defrost, blowing out cold air, and then has to make up those BTUs, in addition to the load of the space, at a time when it is struggling to begin with due to low outside temps. That extra energy it now consumes is not included in the rated COP, among other things. Thus real life efficiencies are about 30% below rated ones in NYS climate.

Posted By docjenser on 10 Oct 2015 03:27 PM

Posted By logbuilder7 on 10 Oct 2015 10:51 AM

Posted By Dana1 on 07 Oct 2015 02:14 PM
But I'll grant that can't easily get radiant floor heating out of a mini-split, ducted or otherwise! :-)

Cheap air source chillers (Chilltrix or others) aren't really suitable for the climate- most don't even have output ratings below +25F or so. That's fine in climate zone 3, or marine zone 4, but for zone 5/6 fuggedaboutdit.

Concentrate on the building envelope first, run the load numbers, and report back. With a fairly simple building shape and some careful decisions on window sizing/performance/placement you'd be able to hit Net Zero fairly easily following the whole-assembly R guidance in table 3 of in the BA-1005 document. With a Net-Zero-Capable building envelope the design heat load will come under 25,000 BTU/hr or even under 20,000 BTU/hr, making the HVAC systems cheaper and simpler to decide on.

Sorry guys, but a lot of this discussion is well over my head. Load numbers will be difficult. I am building a log home with raw un-milled logs. Because of this I am assuming that I won't have the most air-tight envelope although, many people who have built with this style talk about amazing thermal performance. This is partly due to thermal mass of the logs. I haven't been able to find any 'scientific' info on log walls for insulating purposes. The house will be 40x40 square, with an ICF walkout basement. 17' high walls and cathedral ceilings. The south facing wall will be loaded with windows and I am planning on 12" of EPS foam for the roof insulation. Using some basic calculators I have found online I need somewhere between 70-85k btu. Considering I am ONLY interested in radiant heating (ducts blow too much dust around in a log home, and due to the high ceilings, I want the ehat at the floor) - is the Chillix product mentioned here the best way to go? In terms of cost effective heating/ low utility bills for the next 50 years?

In your climate, with the capacity needed, you won't get there in a cost efficient way with air sourced heat pumps. You need a system which does not bow down when you need it the most, and with radiant, you need a bit of extra capacity to respond in a reasonable amount of time to the thermal inertia. In my book, with what you are describing, you need about 10 tons of system capacity, including hot water generating capacity. Upstate climate is not very different than Buffalo NY climate.
Most important thing will be your radiant floor design, and the load side of your system.

I am in Rochester, so climate is the same as Buffalo. The Geothermal guy I spoke with said I would need 4-5 tons depending on how much DHW I wanted to heat.

*** I should add this installer was familiar with log home builds and has put systems in them before.

Posted By logbuilder7 on 11 Oct 2015 09:17 AM
*** I should add this installer was familiar with log home builds and has put systems in them before.

Well, a 5 ton unit usually has a capacity of 50 KBTU/h at 32 EWT. If your heatloss is at the lower end of your calculations (70 KBTU/h) , and you have internal gains of about 10 KBTU, if my math is correct you are still 10 KBTU short. That does not account for your hot water yet. More importantly, it does not account for the extra capacity yet which is needed to heat up the floors when the temps drop quickly in the evening, So you need to heat up the thermal mass of the floors first before any BTUs go into the space.
What is the radiant system you plan to install? Staple up from below? top of the subfloor?

What level of details was in the heat loss calculator you used, and what did you put in for the log walls? And what type of windows? And what design temperature are you using?

Given the cost of a 5 or 10 ton system, it's worth investing in doing the analysis carefully ... or considering insulating the walls.

A key part of heat pump design is not sizing it to handle worse case heating load - peaks loads can be more cost effectively handled with some resistance heat (overhead radiant, baseboard, etc). Heating the air/objects may be acceptable for periods where the floor is catching up too slowly (only on the coldest days do you not have excess HP capacity).

First it is a log home with a big front of windows, tough to add insulation.

Second, there is no ductwork (again, it is a log home!), the OP stated that he might consider adding a ductless air handler down the road. so how do you heat the air?

Third, the extra heating capacity needed every night to heat up the the floors is not a worse case heating load, it will happen every night, and it would be very inefficient to do this via supplement electric heat (electric heat element in the buffer tank?).

Gentlemen, this is not a scenario with a forced air heatpump whiteout much thermal inertia in the delivery system. The key part of hydronic heat pump system design is to understand those differences.

I did a highly insulated wall, mainly because these logs will be 20" plus and they hold heat extremely well. I have used a couple of calculators and they have all had similar results however, by changing one small detail they can swing it from 60k btu to 80k btu.

Posted By logbuilder7 on 27 Sep 2015 03:24 PM
I am in the planning stage of building a new home, and because I won't have access to natural gas at my building site, I am looking into geothermal as an way to heat the home. Upstate NY, zone 5 (but nearly zone 6) well insulated 2400 sf house with 1600 sf basement (ICF). I am planning on radiant heat and either no AC, or a ductless unit added afterwards. Since the costs of the system are so expensive, I am wondering if people would/could recommend a DIY kit. Since I have plenty of acreage and will already have bulldozers and backhoes on site, I feel like I should be able to at least install the loops myself (plus avoid any mark up from an installer). What manufacturer/kits would you recommend?

What you plan to use Cpvc, PP, PEX or PEX-AL-PEX in your project? And what you mean well-insulated. If possible give me more details. I am planned make my own GEOthermal system.
Thank you

Pex - al - pex, by well insulated I mean the calculators I found online gave you a choice of poorly insulated home, average insulated, or well insulated and I chose well insulated.

1) What size of pex - al - pex you used 1/2" inch like this http://www.canarsee.com/pex/pipe/1-...pex-tubing  is OKAY?
2) How many loops you did? Which diameter? And how deep your trench?

Thank you

Posted By logbuilder7 on 12 Oct 2015 10:05 AM
I did a highly insulated wall, mainly because these logs will be 20" plus and they hold heat extremely well. I have used a couple of calculators and they have all had similar results however, by changing one small detail they can swing it from 60k btu to 80k btu.

The only way a 2400' house with a 1600' basement  with "...highly insulated wall..." construction to hit 60K+ for a true heat load in a zone 5 edge-of-6  location would be with some windows left open, or a large amount of uninsulated above-grade insulation.

Tight code-min construction is coming in around ~12 BTU/hr-ft^2 @ 0F these days, and "...highly insulate..." houses are often well under 10 BTU/hr-ft^2 @ 0F.  

For reference, a recent Manual-J on house that had been doubled in size to 3400' by a large addition mirroring the original house had 1700' fully above grade, the other 1700' a walk-out basement came in at about 46,000 BTU/hr @ 0F.   That's a ratio of 13.5 BTU/ hr-ft^2, but heavily weighed down by the east half of the house was leaky 1970s 2x4 /R12 construction with R19s in a cathedral ceiling. The new west half is code-min 2x6/R20.  Were it all code-min it would have been in the 10s or 11s of BTU/ hr-ft^2.

A well insulated house 2400' house with 1600' of basement insulated to current code min R15 c.i. should  run under 30,000 BTU/hr @ 0F, which is still under 40,000BTU/hr at -25F (or whatever your absolute all time record low is in that zone 5/6 location.)

The notion that current mini-split technology delivers seasonal efficiency 30% lower than nameplate efficiency in a zone 5A climate is not supportable by the data.  Opinions based on the performance of decade+ old models like the -GExxNA Mitsubishi  not designed for cold climate use need to be discounted heavily- it's a straw-man type argument.  Even the older Mitsubishi FEs hit nameplate efficiency in zone 5A at 1.25x oversizing, and almost hit those in zone 6B (which is a bit drier, with less defrost time than in zone 6A.)

So you are saying I only need ~40k BTU, at most? PS: How come some boilers are rated at "up to 200k BTU an hour"?? I looked at Navian NCB and thats what was listed for it.

Posted By logbuilder7 on 13 Oct 2015 03:03 PM
So you are saying I only need ~40k BTU, at most? PS: How come some boilers are rated at "up to 200k BTU an hour"?? I looked at Navian NCB and thats what was listed for it.

What I'm saying is that it pays to do a legitimate & careful heat load calculation before dropping 40-50 grand on a heating system (even if you have to hire an engineer to run the numbers for you) and that whatever tools you've been running the estimates on are giving you some insanely high numbers for any house that would legitimately be called " high performance" or "very well insulated".

A Navien combi-boiler needs the bigger burner to support the instantaneous loads of high potable water flows. A flow of 6 gallons per minute with a 70F rise (say, from 35F to 105F) is 210 BTU/hr.  It would be insane to install a Navien NCB in a building that had a heat load that high, but a house with two showers that might be used at the same time could need one.

Most 2000' code-min houses could be heated with a 50,000 BTU/hr-input modulating condensing boiler, with an indirect fired tank for the hot water operated as a "priority zone".

Posted By Dana1 on 13 Oct 2015 01:36 PM

Posted By logbuilder7 on 12 Oct 2015 10:05 AM
I did a highly insulated wall, mainly because these logs will be 20" plus and they hold heat extremely well. I have used a couple of calculators and they have all had similar results however, by changing one small detail they can swing it from 60k btu to 80k btu.

The only way a 2400' house with a 1600' basement  with "...highly insulated wall..." construction to hit 60K+ for a true heat load in a zone 5 edge-of-6  location would be with some windows left open, or a large amount of uninsulated above-grade insulation.

Tight code-min construction is coming in around ~12 BTU/hr-ft^2 @ 0F these days, and "...highly insulate..." houses are often well under 10 BTU/hr-ft^2 @ 0F.  

For reference, a recent Manual-J on house that had been doubled in size to 3400' by a large addition mirroring the original house had 1700' fully above grade, the other 1700' a walk-out basement came in at about 46,000 BTU/hr @ 0F.   That's a ratio of 13.5 BTU/ hr-ft^2, but heavily weighed down by the east half of the house was leaky 1970s 2x4 /R12 construction with R19s in a cathedral ceiling. The new west half is code-min 2x6/R20.  Were it all code-min it would have been in the 10s or 11s of BTU/ hr-ft^2.

A well insulated house 2400' house with 1600' of basement insulated to current code min R15 c.i. should  run under 30,000 BTU/hr @ 0F, which is still under 40,000BTU/hr at -25F (or whatever your absolute all time record low is in that zone 5/6 location.)

The notion that current mini-split technology delivers seasonal efficiency 30% lower than nameplate efficiency in a zone 5A climate is not supportable by the data.  Opinions based on the performance of decade+ old models like the -GExxNA Mitsubishi  not designed for cold climate use need to be discounted heavily- it's a straw-man type argument.  Even the older Mitsubishi FEs hit nameplate efficiency in zone 5A at 1.25x oversizing, and almost hit those in zone 6B (which is a bit drier, with less defrost time than in zone 6A.)

May be I am missing something, but he is building a LOG HOME!!!
Remember, when buildings have thermal bridges, where a wood frame stud actually conducts the heat from the inside to the outside, which you can see on a thermal camera! Here, the whole house is a thermal bridge! Add to that 17 feet high walls, cathedral ceilings, the southern wall plastered with glass windows with an R value around 3, and I would be curious how it can be assumed that this scenario performs with a heat loss between 10-12 btus/sqf?
Logs dry out, shrink, and are subject to higher air infiltration. While their overall thermal behavior is good due to their higher thermal mass (storing solar energy during the day, dispensing it at night), meaning the annual energy consumption might be similar, they can swing more, requiring much more peak load capacity, when the solar gain is not there for a few days, or at night after the stored thermal energy is depleted.
Now combine this with a slower responding radiant floor, and you need some serious peak capacity to keep a log house comfortable.

Not sure where you have the $40-50K number from. Even with a 30Kbtu heat load (which you don't have here, you probably need 60 kbtu for a few hours (especially with additional DHW load) to help you out to overcome the thermal inertia.

Now, be aware that a system needing a higher peak capacity, does not necessarily need a bigger loop field, since the total heat extracted is not necessarily more. So all you need is a bigger heatpump and ensure the flow, something that comes probably $8000 more for a 10 ton w-w versus a 5 ton.
Here is a link which describes pretty good the thermal performances of log homes which are important to understand.
http://energy.gov/energysaver/energy-efficiency-log-homes

Yes, it's a log home, as decribed: " ...these logs will be 20" plus 20" logs. " That's not a thermal bridge.

With 20" logs there both R-value well in excess of code-min wall performance just on raw insulation value, and a very significant thermal-mass effect. It should beat minimal ICF wall performance if air tightness can be maintained. Air tightness is the Achilles heel of log construction more so than raw R-value at 12" or fatter thickness. But 3ACH/50 air tightness is achievalbe.

Doubling the size of a heating system for DHW loads is a pretty silly approach compared to buffering domestic hot water in tanks. A heat pump that can deliver 30KBTU/hr at DHW temps would have faster recovery times than a typical electric HW heater. A heat pump water heater drawing it's heat from the room air would be able to utilize the thermal mass of the house, and it wouldn't increase the necessary size of the GSHP by more than a tiny fraction.

Do you think anybody can design & implement a GSHP system that delivers his presumed 60-80KBTU/hr for less than $40-50K and still make a living? (I'm not even talking the more expensive southern New England pricing here, since it's not in southern New England.)

If the real heat load is something like half his presumptive loads, the cost won't be half of $40-50K, but it'll still be well worth paying for the engineering analysis to come up with the real number, and sized the GSHP system accordingly.

Posted By Dana1 on 14 Oct 2015 10:47 AM
Yes, it's a log home, as decribed: " ...these logs will be 20" plus 20" logs. " That's not a thermal bridge.

With 20" logs there both R-value well in excess of code-min wall performance just on raw insulation value, and a very significant thermal-mass effect. It should beat minimal ICF wall performance if air tightness can be maintained. Air tightness is the Achilles heel of log construction more so than raw R-value at 12" or fatter thickness. But 3ACH/50 air tightness is achievalbe.

Doubling the size of a heating system for DHW loads is a pretty silly approach compared to buffering domestic hot water in tanks. A heat pump that can deliver 30KBTU/hr at DHW temps would have faster recovery times than a typical electric HW heater. A heat pump water heater drawing it's heat from the room air would be able to utilize the thermal mass of the house, and it wouldn't increase the necessary size of the GSHP by more than a tiny fraction.

Do you think anybody can design & implement a GSHP system that delivers his presumed 60-80KBTU/hr for less than $40-50K and still make a living? (I'm not even talking the more expensive southern New England pricing here, since it's not in southern New England.)

If the real heat load is something like half his presumptive loads, the cost won't be half of $40-50K, but it'll still be well worth paying for the engineering analysis to come up with the real number, and sized the GSHP system accordingly.

The main issue is the drying and shrinking wood, causing air infiltration over time, and the high thermal mass on days without solar gain. Lesser of an issue with a forced air system, bigger issue with a slow responding radiant floor.The doubling is not for DHW, it is the extra capacity needed to overcome the thermal mass of the floors and the house, in order to put some heat into the house. The DHW need is small compared to that load. It is not silly, it is real. It will take hours to respond to a heat call, unless you have extra capacity.
Once you have the full hot water generating capacity of a hydronic heat pump, why putting in an air sourced heap pump within the thermal envelope?
Again, a 10 ton system does not have to be significantly more expensive, since only the heatpump size is different, taking the same time to bold in.
What is the alternative? Most w-w energy star rated HPs are a max of 5 tons, making about 50 kbtus/h, the next energy star units are 7 or 10 tons I am aware of, the 7 ton being a high temp, costing as much as the 10 ton. We install them for $33K without DHW, and $37 with DHW (no A/C, not including the floors). It is about $9K more than a 5 ton.
Again, the system needs only higher peak capacity, the rest of the system, including the loop field, can be much smaller.