Hybrid heating system on the cheap
Building a new home this spring… Cape, full basement (1450 sf), loft area over 1/2 of first floor using SIP’s, located in Minnesota. To get the best heating for the buck, does it make sense to run hydronic in the basement slab heated with an electric water heater taking advantage of off peak rates and run duct work to the rest of the home attached to conventional furnace, AC and ventilation?
I’m guessing having the two systems would make this twice as expensive as just FA heating– not sure it would have great payback.
–Steve
Replies
May want to pose your question to: heatinghelp.com. I'd change the title though as many pros hang out there and won't appreciate the phrase "on the cheap".
Randy
Edited 10/30/2006 1:31 pm ET by Reg
No, it doesn't "... make sense to run hydronic in the basement slab heated with an electric water heater taking advantage of off peak rates and run duct work to the rest of the home attached to conventional furnace, AC and ventilation.", based on the title of your post. For that matter, it doen't make any more sense to use a water heater for comfort heat than it does to use your stove and your dryer for comfort heat.
The least expensive all inclusive system you can get for your home is a gas fired furnace with an air conditioner.
One poster here will tell you that his electric rates in Minnesota are the cheapest in the county. Though when asked, he didn't know what those rates were! Do you know what are you electric rates at various times of the year? And what changes are on the immediate horizon? Have you counted on the fact that your electric rates are likely to double in the next ten years?
In terms of fuel utilization efficieny, it is very hard to beat a 94% efficient gas furnace (AFUE). Warm floors are nice, but not a necessity and not the least expensive way to heat your home. There is never going to be a "payback" with a hybrid system or a hydronic system over a single, high efficiency FA system. Is this the absolute most comfortable system you can get? No, but you want cheap.
Cheap, efficient, or most comfortable? Pick two. You can't have all three. Not that a forced air doesn't provide good comfort, it does. Or at least it can. You go too cheap, you'll end up with what you pay for.
Tim-- I've received other advice similar to yours and I'm leaning that way. Thanks for your input.The rate I have available may well be the cheapest-- 3.4cents/kW. Part of a coop set up in the western suburbs of Minneapolis. Hasn't changed in 25 years. I've used that program in my present house for some of our heating-- not too many hours of interruption. May go with a standard furnace but look at adding a plennum heater to take advantage of that.-Steve
3.4c/kwh is a very good rate, but the fact that is hasn't changed in 25 years is, or should be, a big red flag if doing an enery/cost analysis.
Don't misunderstand my post, I think very highly of radiant, hydronic heat. The wholesale cost of the tubing (1/2" pexA barrier type) is $0.50/ft. Imbedded in concrete, 12" o.c., works out to about 1 linear ft/sq ft. Once you factor in a reasonable retail markup, insulation amd installation, count on the tubing in the basement slab to cost $1 to $1.50/sq ft.
Personally, if I were starting from scratch with my own home, I would get a very efficient (modulating/condensing) boiler to provide infloor heat and hydro/forced air type of units for tempering ventilation, some space heat and AC, plus an indirect water heater powered from the boiler. In the long run, in an area where significant HP air side heat is not available, this is the least expensive type of fuel fired system to operate and would offer exceptional comfort, practically endless domestic hot water and do so at as high efficiency as is reasonable acheiveable today. Else, a ground source (geo-exchange) heat pump system, either completley geo or a hybrid would be the way to go. These are not available "on the cheap" however. Life is full of compromises.
Merty,
I just built with SIPs and RFH, with a Mod Con boiler.
Honestly I really like the system but... I don't have warm floors.
With the low heat loss of the SIPs and the outdoor temp. sensor with the boiler my floors are "not cold" yet only feel warm on the coldest days.
If I build again I will consider the forced air over hydronic Lifebreath furnace/HRV/filter combination with RFH in the basement.
Garett
The reason for doing the hydronic heat would be for comfort, not economy. You're unlikely to save money vs heating totally with natural gas.
(And personally I think that in-floor heating in basements is overrated. Especially if foam is placed below the slab, the floors will not be that cold. Much of the coldness ascribed to basements is due to the poor airflow that is frequently present in DIY basement fix-ups, often with the heat coming in at ceiling level and no zoning of the furnace.)
With those cheap rates you may want to consider a heat pump, especially a ground source heat pump. More money up front, certainly, but the GS unit is probably your lowest cost to operate.
OTOH, gas forced air furnaces are pretty cheap, reliable, and fungible -- you're unlikely to ever be "stuck" for very long due to a malfunction, an important consideration in MN.
I suggest basement in floor heat because I feel it is the most cost effective way to make a basement comfortable. Insulation is a must and tubing and controls are relatively cheap. Garett