Hi everyone, I'm in the process of planning a Hydro-air/ basement radiant heating sysytem for a 1100sq/ft house(2050 heated w/basement) in Alberta Canada. The house currently is forced air zoned mainfloor/basement with seperate returns and supply trunks with two seperate old furnaces (160000 BTu total+38000 BTu water heater!!!!), Heatloss has been calculated at 44000-52000BTu @-25C (depending on either my HVAC program calc or my Hvac guy's calculations)

For boiler I've decided either a TT solo 110(30-110), Laars Mascot II LMH125(25-125), or if available when this project gets going a Lochinvar WHN 110 (22-110). For domestic either a 40 gal TT smart or a 34 gal Thermo2000 turbomax (was recomended to me).

My question is: I plan on getting the system running only on the fan coil (Energy saving products LVE-1050) with this single unit tied into the both heating and return trunks and setting it at 160F as well as using the outdoor reset on the boiler to allow it to drop to 120F on high outdoor temp. This would have the fan coil put out 64000 BTu at the coldest design day. This would keep the boiler condensing except for the coldest days.

I don't plan on adding the basement radiant for at least a year or two (maybe three LOL?), the other option would be to leave the house zoned as is and use two fancoils, one for mainfloor and one for the basement and set them at 140F, this basically gives me 80000-90000 Btu output total for both fancoils. I probably wouldn't need the infloor at this point.

Would the single fancoil be enough to comfortably heat this house for the intrim? I would prefer to have a mix of hydro-air and radiant rather than straight hydro air as I've been told the discharge temps off hydro fancoils are significantly cooler than a furnace--although these fancoils are 6 row.

--In case you guys are wondering why not do one or two hi-efficency forced air furnaces and be done with it... it's cost, the price to do two hi-eff furnaces is only slightly less than this system and I still have DHW to think about so if you add a tankless it's about the same.-

Thanks

You are on the right track but.

First, the boiler is too big for the load, which is likely lower than either heat load (especially if radiant specific software was not employed). If you use the high number either boiler will have twice the output needed on the coldest day of the year, every other day the boiler output will be MORE than twice too much. Poor efficiency, comfort and reliability will follow.

Second, fan coil temperature at the register is based on design water temperature and coil size (the guys at ESP know all about this). Fancoils and condensing boilers are not a match made in heaven. You do it because it is cheaper than radiant floor.

Finally, it makes no sense to put a fancoil in a basement. You can take a considerable portion of the load off with the basement radiant and condense the whole time.

Professional hydronic design is the answer.

Posted By Trumpfan on 25 Jan 2011 08:06 PM
Hi everyone, I'm in the process of planning a Hydro-air/ basement radiant heating sysytem for a 1100sq/ft house(2050 heated w/basement) in Alberta Canada. The house currently is forced air zoned mainfloor/basement with seperate returns and supply trunks with two seperate old furnaces (160000 BTu total+38000 BTu water heater!!!!), Heatloss has been calculated at 44000-52000BTu @-25C (depending on either my HVAC program calc or my Hvac guy's calculations)

For boiler I've decided either a TT solo 110(30-110), Laars Mascot II LMH125(25-125), or if available when this project gets going a Lochinvar WHN 110 (22-110). For domestic either a 40 gal TT smart or a 34 gal Thermo2000 turbomax (was recomended to me).

My question is: I plan on getting the system running only on the fan coil (Energy saving products LVE-1050) with this single unit tied into the both heating and return trunks and setting it at 160F as well as using the outdoor reset on the boiler to allow it to drop to 120F on high outdoor temp. This would have the fan coil put out 64000 BTu at the coldest design day. This would keep the boiler condensing except for the coldest days.

I don't plan on adding the basement radiant for at least a year or two (maybe three LOL?), the other option would be to leave the house zoned as is and use two fancoils, one for mainfloor and one for the basement and set them at 140F, this basically gives me 80000-90000 Btu output total for both fancoils. I probably wouldn't need the infloor at this point.

Would the single fancoil be enough to comfortably heat this house for the intrim? I would prefer to have a mix of hydro-air and radiant rather than straight hydro air as I've been told the discharge temps off hydro fancoils are significantly cooler than a furnace--although these fancoils are 6 row.

--In case you guys are wondering why not do one or two hi-efficency forced air furnaces and be done with it... it's cost, the price to do two hi-eff furnaces is only slightly less than this system and I still have DHW to think about so if you add a tankless it's about the same.-

Thanks

Trumpfan - Triple H Hydronics in Calgary handles Lochinvar 403-236-1211 He can also design the system for you.

So 1/2 of my system is up and running, We eventually went with a single DC motor ESP Lo-vel. fancoil for the entire house with entirely new ductwork to match, the fan coil is set at 160 deg at design day temp. It's running with the fan in constant low speed and seems to have kept up quite nicely this winter although it has been mild for here. The rest of the system is a Lochinvar WHN110 and a turbomax 23 indirect. I've seen a some short cycling when temps are in the 5-8C range(which is abnormal for this time of year) It recovers the small indirect in less than 4 min!

The second part of the system the basement infloor is now underway. My heat load for the basement is 20 BTU/ft and we were going to plan on using Roth board or Schluter Bekotec and thin pour. The supplier of the Roth board wants to install it over the slab with no supplemental insulation, I believe it's R3-4 as installed. I've also looked at the bekotec system it's R2 as it sits, I would like to put extra insulation under the boards -the slab is uninsulated but has vapor barrier and 3" sand base as per the house plans from 30yrs ago. I'm being told that all I need is a thermal break beween the old slab and the system I would install. I personally would like to see at least R5-10 under the infloor. Is this enough? I have only 2.5" to work with before the height loss becomes really noticable.

Can Roth board really be put down with out supplemental insulation?

20 BTU/sq ft for a basement is huge. Is this not a fully buried basement, or is it not an insulated basement? Certainly you should insulate the walls...

typically roth is installed as is with no further insulation. it's not strictly ideal but it's certainly adequate in most basement retrofit situations, and height is usually an issue.

The basement is fully buried and insulated to at least r16 (2x4) and 3/4 styro SM on the walls with a foamed rim joist. The final load calcs were done at -32C as opposed to -25C. Edmonton's climate is easily a 10000 HHD climate. Although I've actually pushed the design temp back on the outdoor reset to -35C for the fan coil.

The basement heat loss was calculated at over 18000 BTU at these design conditions. So at 1000 sq ft for the basement 20BTU/ft is not unreasonable.

Would there be a much of a performance difference between the Roth installed minus insulation under it and Schluter Bekotec and a thin pour? Seems like it would be response vs thermal mass arguement. I've seen Roth in use and the supplier is really pushing it but I find it spendy vs other options.

Setback would not be used in the basement and hopefully it will offload the fancoil a bit. When this house was heated with the dual furnaces the oversize basement furnace could keep the whole house at 21C until -5 or -10C using only warm air rising from the basement.

your 20 BTU/sq ft for a basement is actually quite unreasonable. I just ran your scenario at -25 deg F outdoor (-32 C) for an 8 foot deep basement, 7 foot buried, R5 slab R16 walls and a fairly ridiculous 0.35 ACH with conditioned space above and... with no windows... I haven't even broken 10 BTU/sq ft. Which jibes completely with my typical basement experience even in cold climates.

I suggest that your numbers are pretty heavily off for some reason. Also, if your upper floor is calculating in at the remainder of that 44-52k BTU load then you basically have a nearly uninsulated or heavily windowed house... you'd have 30-40+ BTUs/sq ft up there which, frankly, is ridiculous.

not to be insulting, but seriously... unless your insulation is far under spec you aren't even in the ballpark, and this looks like a solo 60 to me, at most.

Rob is right.

We do heat loads for Canadians every week. Sounds like a DIY heat load to me. Oversized equipment will cost more to install, maintain, operate and will almost always compromise comfort as well.

It costs less to have an experienced professional perform a computer generated heat load than to "guess-by-golly" and buy hydronic heating products you don't need.

I do get a kick out of the Internet Educated arguing with Rob hehehehehee

The heat load is likely 100% inflated.

The heat load analysis was completed by a hydronic designer (as required by the building code) to pull a permit for a hydronic system. It was completed by the supplier and installer of the fancoil. I also modeled my house using Hot2000 software, my load was somewhat less than theirs. There are some differences in The infiltration numbers It appears that the installer used my blower door numbers of 2.67 ACH@50kpa, I'm not sure if the software he used takes into account the press difference.

The software I used has parameters for both ACH values. I plugged in 0.33ACH this morning and came up with 13670 BTU for the basement

The boiler was chosen by myself and my installer- I did wish to go with a smaller boiler as Badger did mention last year but I was talked out of it because of what might be percieved as poor DHW performance. What sold me on it was min modulation I was told that the difference between 16000 and 21000 was mininmal-It now looks like that 5000 btu is half my basement loss.

I'm open to being educated thats why I'm here, but how would you feel if you were working on this project and the homeowner kept telling you that some guy on the internet says you're doing it wrong?

A small part of the btu load as required by the boiler probably comes from derating the gas for high altitude. Probably 10%??

it's 16k to 30k min mod from the 60 to the 110... big jump. this is, unfortunately, not a rare thing. supply houses and contractors routinely upsize equipment to avoid callbacks and because they are not running good numbers so they use it for a safety margin. you can get around DHW performance by using a larger tank but that too requires someone doing some good math.

on the plus side you shouldn't have any major issues with the roth in this case.

You can lead a horse to water...

I wonder why people come to ask, only to ignore?

Feel free to refer your "designer", "distributor", etc. to the anwers.

http://www.badgerboilerservice.com/contractor.html

Posted By NRT.Rob on 09 Feb 2012 09:07 AM
it's 16k to 30k min mod from the 60 to the 110... big jump. this is, unfortunately, not a rare thing. supply houses and contractors routinely upsize equipment to avoid callbacks and because they are not running good numbers so they use it for a safety margin. you can get around DHW performance by using a larger tank but that too requires someone doing some good math.

on the plus side you shouldn't have any major issues with the roth in this case.

Thanks for the insight on the Roth.