Heat Source Options for Radiant Floor

mike14

I'm putting in 900 square feet of slab over pour in a basement with a seperate zone for a 150 square foot staple up to supplement a cold room on the first floor. The heat loss shows about 25,000 Btu. I want a closed system so need a separete heat source. I don't have room for a seperate hot water heater so I was looking at instantaneous water heaters like the Takagi TK1 or TK2. I like the modulating feature and it will fit within my space and budget. My Contractor says that I'll have alot of problems with this unit short cycling because it won't modulate low enough. He's pushing for an electric unit like the Seisco RA-14 or RA-18. The Seisco looks like it will do the job, but I'm concerned about the cost of operation vs. the gas fired Takagi. He says to run it off-peak and it will be roughly the same.
I've been reading this board for months and I trust you guys. What do you think?

joel_14

why?

don't you just tap it off your boiler??

mike14

I don't have a boiler. The rest of the house is gas fired forced air. I'm just finishing the basement and I know forced air won't cut down there. I want radiant floor so I can actually use the space in the winter. (Minnesota)

hot_rod

Compare utility rates

generally gas, oil, or lp come out better. I'm not a fan of instantanous for radiant...but!

Watch the Seisco I've had problems with reset trippings when running them up near their temperature limit. What temperatures do you require for that staple up? Do you need a second, lower, temperature for the slab?

Not sure how you use the Seisco on the off hour rates? If it's used to charge a buffer tank, might just as well use an electric hw tank with the proper KW elements for the load!

hot rod

flange

if it were me, i would "find" the room for a gas hot water heater over electric anything. or even a low mass boiler.those are pretty small.

Ted_5

Think out of the box

Mike if you put in a small Vitodens 90,000 down to 24,000 on
natural gas and 81,000 down to 24,000 on LP and use the extra heat in other places, a reheat coil in your ductwork
DHW, some rads, towal warmer in the master bath??? I am in
that area, so if you need some help, let me know.

Ted

J.C.A.

I think...

Teds got the right idea . Rid yourself of the furnace , install a fan/coil unit and keep the A/C option open , start making your heat and hot water as it "can be done" to a spankin new boiler.

I know it sounds expensive...but in the long run ? If your planning to be in the space for a while , it'll pay you back in both comfort and dollars.

If there's space for a furnace ...there,s space for a boiler and water heater . Check back for the picture Wayco Wayne asked Scott Milne for a couple weeks back .
That puppy had a footprint of about 4 square ft.(although it was about 6'4" tall. Just a thought . Chris