advise needed on electric boiler and manifold
Last Post 21 Aug 2015 04:16 PM by Dana1. 7 Replies.
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timsenUser is Offline
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18 Aug 2015 07:44 PM
Hey all, I'm in the process of remodeling and adding radiant floor heat in some rooms. It's in NorCal and very well insulated so heating will only be used for comfort heating some days in winter. The system needs to provide 4 warmboard loops (2 for 600sf living room, 1 each for 250sf bedrooms). I'm thinking of getting this manifold: 4-Loop 1-1/4" Stainless Steel Radiant Heat Manifold And this boiler: Argo AT204510C electric boiler Reason for electric boiler is that we have a solar system installed so electric power is much cheaper than gas. Is this the right boiler for the installation or maybe too big/powerful? Note: My plumber will install the systems but asked me to provide the parts. Thanks, Tim
Blueridgecompany.comUser is Offline
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19 Aug 2015 04:38 PM
Hi Tim,
The Argo you mention is 68,000 BTU,
Capacity like that in a well insulated house could easily heat a 4,000 square foot house.
Sounds like way overkill.
Have a look at our little Thermolec units, you are probably looking for 15,000 BTU or less to cover all heating.
These ship preassembled, have outdoor reset, if used for supplemental heat you could likely get by with the 10,000 BTU unit.
http://www.blueridgecompany.com/radiant/hydronic/738/rht-prefabricated-electric-1-zone-boiler-panels
Dan
Dan <br>BlueRidgeCompany.com
jonrUser is Offline
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19 Aug 2015 05:52 PM
Another homeowner that finds that solar PV powering resistance heating isn't crazy.....
Blueridgecompany.comUser is Offline
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19 Aug 2015 07:34 PM
Not so sure on that.
I just built a 2500 sq ft spec home,
5K pv panels, grid tie.
Electric boiler for in floor, and heat pump for forced air cool /heat. The heat pump only covers two thirds of house due to design. In floor is 100% of building, multiple zones.
I live on a island, propane is high, oil is high, Natural gas not available, electric is least expensive option, grid tie brings it down more.
So an option. yes.
All sorts of different reasons for a electric boiler as a good choice, especially if it is a small supplemental area, there very easy.
Dan
Dan <br>BlueRidgeCompany.com
BadgerBoilerMNUser is Offline
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19 Aug 2015 09:55 PM
Dan is right.

Solar resistance heating...

Not yet.
MA<br>www.badgerboilerservice.com
Dana1User is Offline
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20 Aug 2015 04:16 PM
For heating 1100' of total space it's probably not very expensive to run in a "...very well insulated..." house, but a radiant floor is possibly pointless, since the only time the floor would be warm enough to notice would be in the pre-dawn hours of the coldest night of the year.

In a very well insulated house probably looking at something like 5-6000 BTU/hr of load, possibly less at most northern California outside design temps, which means even a 2 kw boiler would probably cut it.

Got a ZIP code so we can figure out your 99% and 1% outside design temps? Or just look it up and tell us what the 99% temperature is:

www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/Outdoor_Design_Conditions_508.pdf

(The town-by-town design temp listings for CA start on p.36, in PDF pagination.)

The "right" way to do it would be to run a Manual-J type load calc on those rooms...
ronmarUser is Offline
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20 Aug 2015 05:11 PM
Need design temps and a description of what "Very Well Insulated" means to solve this equation. Window areas and U factor and ventilation/infiltration rate would also be usefull... 68K BTU does sound like overkill, and 5-6KBTU might not be enough. Untill you calculate your actual heat load it is all just a guess...
Dana1User is Offline
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21 Aug 2015 04:16 PM
For reference 68,000 BTU/hour is what it takes to heat my not-so-well insulated antique 2400' house when it's 50F below zero outside.

At a typical N.Cal outside design temp of 40F (say Eureka CA's 99% temperature bin of 41F) I can heat the whole 2400' with less than 15,000 BTU/hr of boiler output, and taking any typical 1100' chunk of it would need about 6500 BTU/hr. That is less than 1/10th of the output of the ridiculous 68K electric boiler.

A "...very well insulated.." 1100' should take less than that, unless it happens to be the 1100' with lots of floor to ceiling window or something. At normal 15% window/floor area ratios even a 2x6 framed house w/R19s and crummy clear-glass U0.50 windows would be in the 5-6K range (or less) as long as the windows are closed.

That's not a Manual-J, but it's better than a random WAG. (It's an educated WAG! :-) )

A 68K boiler needs a dedicated 100 AMP 240VAC circuit, which would be a pretty silly expense when the peak load would be less than 1/10 that, and COULD be served by a more appropriately sized 2 kw boiler on a 20A 120VAC circuit.

But some folks enjoy the challenge of swatting flies with sledgehammers, eh? ;-)
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