Hot water For Radiant Floor Heating

[Maxfli]

We built a house a few years ago and put Radiant floor heating in a few areas. The kennel and basement are heated via this system, and for now my wife's dogs are getting the most out of this system. I am not real happy with the way the heating guy did the system. Initially it had a 50 gal water heater on it, and when I cranked up both zones I could easily overload the system. They came last winter and put in an 80 Gal water heater and things are better. I really would like to add another zone going between the joists under the master bath, and once again that would probably tax the water tank. I think it should have had a real boiler on the system from day one, but I did not make it clear enough in the purchase contract. Any recommendations as to a boiler, and will it make a big difference in efficiency? The basement is probaly 1500 sq ft, and the kennel is 450 sq ft.

 

[woodlot]

Maxfli, Its been a while but I have designed and built a hydronic radient system from the ground up and I am NOT a HVAC person in any way. Both designing and building were a lot of work, but rewarding. I ended up using an outdoor woodboiler for heating water but had considered using a gas boiler. I beleive you will need what is called a condensing boiler because of the low temps on the return side. There was one brand called "Munchkin" that was highly recommended, that goes back about two years ago when I did my system so my spelling may be off. The hardest thing about doing any HVAC stuff yourself is aquiring the heating plant because most manufacturers will only sell to licensed installers, and only honor a warranty when installed by licensed people, "Munchkin" was not one of those. These types of boilers vent with PVC out the side wall which is nice. Also, my electric company is a co-op and they have alot of electric heating products that I can buy from them, one is an electric boiler specificly designed for radiant systems and is designed to be run "off-peak" at a much reduced rate per kwh. That may not be an option for you but may be worth checking out. Good luck. Here's just one link about the boiler, lots of info out there:
munchkin boiler

 

[Freds]

I used a boiler for underground radiant heat in my kennel (along with supplemental forced air furnace for the AC). It is a Weil-McLain, which I believe a lot of people will say is one heck of a boiler... around here anyway. It also heats my hot water tank, I believe they call it an indirect water heater, but I'm not in the kennel right now...
I installed everything myself with a schematic from the supply house and a few phone calls /forums/images/graemlins/crazy.gif. It has three zones for 1000 sq ft, but I leave all three turned on when it's running.

I went boiler over hot water tank because it is a more commercial type application and the hot water tank just didn't sound like it could do the job. Boilers have my vote, but if you want to add another zone anyway, maybe a second hot water tank would meet your needs for that particular zone. It would be a heck of a lot cheaper.

 

[Sigarms]

Yes, for a radiant system, a boiler is the way to go.

Problem with hot water heater is the the water temp output.

Water heater will only put out 150 degrees or so.

Per sq. ft, depending on the load calulation of the area, you may need to increase the temp. Hot water heater will not do that.

BEST boiler in the world in Buderus. Weil McClain, Burnham, Smith, Lochnivar, Dunkirk (makes at least 8 different namebrands), Crown, Utica, New Yorker will not hold a candle to Buderus.

Just finished up a 2.5 million home. Home owner very happy with his system (he did pay for it).

Issue that you have to look at is water temp per sq. ft. per load for the area and flow rate (VERY IMPORTANT).

If you want it done right, you will pay for it.

MANY factors to involved (lot like infared heaters).

 

[Sigarms]

Munchkin boilers.

80M 25k/74k BTU
140M 43k/129K BTU
199M 61K/183K

"high effieient" over 90% which enables you to vent with PVC (you can also do that with other boilers).

Only thing that I would look at is the amount of water it "handles".

Yes, it would work fine for a radiant job, but... the cost could be "intersting" compared to other brands with the same BTU/efficiency.

Selling point on the the Munchkin is thier weight.

Max weight for the largest unit is only 111 pounds.

When I got into a "kick" selling them to contractors, I could put one in my VW and carry it in to them (can't so that with many other boilers that I can think of).

I sell both of them, would still recomend (sp?) the Buderus over the Munchkin.

Woodlot, love that site you posted. Pricing is very interesting /forums/images/graemlins/smirk.gif

I always love it when a "homeowner" screws up a job /forums/images/graemlins/grin.gif

Try to get warranty parts from that site or tech help /forums/images/graemlins/frown.gif

 

[rlw]

I have radiant in my workshop. Last fall I replaced the water heater I was using as the heat source with a Munchkin T80 boiler. The performance of the boiler far surpasses the water heater - it runs less and maintains the temp better. I believe most fully-condensing boilers have a 92+% efficiency versus a water heater that is maybe 60% efficient. With gas prices going sky-high, efficiency is a big deal.

Our gas bill lists the degree days and amount of fuel used the same month last year. Last winter (2004-5) was significantly colder than the previous winter (2003-4) - but I used quite a bit less fuel with the Munchkin. If I recall correctly natural gas prices were about 30+% higher in '04 over '03 and its likely to be worse this year.

I installed the unit myself - pretty easy. I contacted several places for quotes on the unit and the best pricing I got was from Boiler. I got a wide range on the quotes, some were almost 50% higher than what I paid...get lots of quotes.

 

[inveresk]

I'd be happy to provide you with diagrams of a typical u/f heating system. I designed and installed many of them in Scotland where I ran a small design and construction group (I'm a Scottish architect, now living in BC). The files are quite big and I'd need to email them but drop me a PM with your email if they'd be useful and I can get them off to you.

 

[DMF]

I built a 2300 sq. ft. home a couple of years back. The basement, combo great room/kitchen/dining (884 sq. ft. in itself), two bathrooms and an entry way are all heated with the radiant. The three bedrooms are hot water baseboard and everything is heated with the Buderus boiler, no problem other than the price of oil! The Buderus was descibed to us as the top of the line and it appears to be true.

My next project is to tie in one of those outdoor wood burning boilers....