Radiant heat is the coolest...err warmest!

[vi edit]

When I built my house a few years ago I plumbed in my basement slab to be ready for a radiant heat warming system. Last winter I retrofitted a good portion of my main floor to have loops running under the majority of it. I made my own heat transfer plates and looped 3 runs of about 250 feet of Pex under my kitchen, eat in kitchen, foyer, and master bath.

Here's what my basement looked like before the slab was poured:
https://7kb11w.bay.livefilestore.co...u5czBCVkbZvYl5sISBz-eYlGd/IMG_4160.jpg?psid=1

Last winter was fairly atypical...not cold at all. March had like 2 weeks that were 80 degrees and I never got around to finishing up the system.

This year it's been cooler and I finally sucked it up and got my system finished.

I've got an integrated radiant panel mounted to run the system and had a plumber put in a 2nd gas fueled water heater for the heating source.

Here's what my mess looks like in one corner of the basement:
https://hen6qa.bay.livefilestore.co...3zWluGy-iFbu-smTXX/20130122_065130.jpg?psid=1

Long story short...this setup has wildly exceeded my expectations. I installed the heater when the outside temp was around 5F. After an initial slab warm up of about 6 hours my basement was an absolutely balmy 73 degrees. I had to knock it down to 71. And even that is almost uncomfortably warm.

My main floor is largly tile and the staple up blow the subfloor has worked very well. My kitchen floors are very warm under foot and the main floor has a level of comfort I've never had before in the winter. My bathroom can also hit upwards of 75 degrees during the day if I get any sunlight in there. I doubled up the loops under the shower stall which is mostly tile with a big poured slab of concrete for a shower pan. It's a nice toasty warmth under foot when you climb in first thing in the morning.

I wasn't expecting the system to replace my conventional forced air heating system, but it's really trying to do that. Between the warmth coming up from the slab downstairs and the loops under my main floor the main heating system has hardly run. I've got my thermostat set at 71 and it was 15-25F over the weekend and my furnace kicked in about 6 times over the weekend for about 3 minutes each.

The water heater running the radiant runs about every 2 hours for about 10 minutes each time.

My feet are warm, my house is warm, bathroom feels great and the air isn't near as dry since the forced air isn't running as much.

Will be curious to see what my next heating bill comes in at.

 

[SpatiallyAware]

Love it, but as someone who has dealt with all sorts of oddball issues with plastic pipe I'm a little lenient of trusting those sorts of lengths long-term.

 

[rsutoratosu]

nice.. how much did that cost ? i want to add this to my first floor kitchen and bathroom, last week in the NE was super cold

 

[highland145]

Will be curious to see what my next heating bill comes in at.

Total electric? Me too on the bill.

 

[skyking]

I installed the electric wire system under the bathroom floor, none in the shower. I have only tested it so far. It makes sense for us because we don't have gas in the neighborhood.

 

[skyking]

Total electric? Me too on the bill.

Gas water heaters in the OP.

 

[highland145]

Gas water heaters in the OP.

Skimming failure.

 

[vi edit]

Yeah, I'm cooking with gas baby!

Costs...uh...it wasn't cheap.

Roughly $500 in pex tubing for the basement slab
I think I paid another $400'ish for the foam underlayment and tape
Integrated panel was $1400
750' of pex for my main floor staple up was around $200
$500 in misc parts, fittings, manifolds, connectors
$100 for two Aube thermostats
$1700 for the plumber and water heater install
$50 for rolls of aluminum that I stamped myself into transfer plates

A little under $5000. Almost all of it done myself with the exception of the water heater install which I just had no desire to.

I might see some energy costs reductions, but it will take years to ever come close to recovering it. I really just wanted an easy way to heat the basement and keep the main floor more comfortable on those really cold winter days.

 

[iRONic]

Love it, but as someone who has dealt with all sorts of oddball issues with plastic pipe I'm a little lenient of trusting those sorts of lengths long-term.

Leery...?

Nice install, OP.

 

[vi edit]

nice.. how much did that cost ? i want to add this to my first floor kitchen and bathroom, last week in the NE was super cold

Two rooms....*probably* not worth it. You'd be better off going electric grid if you were redoing the floors and just put it on a timer for when you are home.

There are cheaper ways to do radiant but they require a lot of time, effort, and googling answers.

 

[iRONic]

Two rooms....*probably* not worth it. You'd be better off going electric grid if you were redoing the floors and just put it on a timer for when you are home.

There are cheaper ways to do radiant but they require a lot of time, effort, and googling answers.

Yep. We put the electric mats under tile during a bathroom remodel for ~$500 and under Pergo in a bedroom remodel for around $900. (bigger room)

Very very comfy. Not a big hit on our monthly bill.

 

[vi edit]

A couple other tidbits for those interested...

My integrated panel has a Taco 2 zone controller. My manifold will take those little white things you can sort of see stuck on top of the cold loop. Those are actuators that open and close the zone as needed via the thermostat. I've got all three loops for the basement wired up as one "zone".

That single one on the far right is setup for my master bath area. I could put the other two on for the 2 other loops on my main floor but there's not much need. They are running wide open all the time and keeping the main floor pretty consistent at 71 degrees with a little bit of help a couple times a day from the HVAC.

I've got the water heater set at 120 degrees. My outgoing loops for the main floor are 120 degrees, my return is around 100.

Basement slab is set to 71 degrees and after settling the first couple days down it's sitting exactly at that temp where the thermostat is at. I find that very impressive for a system to be able to balance that out and let such a massive slab of heated material come to rest exactly where I wanted it to. I have no idea how often the basement loops run. I've never seen that loop actively running when I've been down there. The water sitting in the lines before it goes into the slab is actually cool to the touch so it's been a while since it last fired.

Thermal masses are fun! Until it hits 65 degrees like the next two days and we are heated out of the house since I can't bring it down from temp quickly. Oh well..it's back down to single digits by Wednesday.

 

[highland145]

Is there some insulation under the basement slab. I'd expect you to lose a lot of heat to the ground otherwise.

 

[amdskip]

$50 for rolls of aluminum that I stamped myself into transfer plates

I'd like to know more about your stamped plates. I can see 2 different pex crimp/expansion systems, different plumbers? Please post your bill too as I would be interested to see that.

 

[vi edit]

Is there some insulation under the basement slab. I'd expect you to lose a lot of heat to the ground otherwise.

Yeah, there's a 1.5" liner of XPS foam board under the slab. I also took 4" strips and lined the rim of the foundation too where the slab would make contact with the foundation wall.

https://7kb11w.bay.livefilestore.co...4pJClytTOcrtBowrqkLLbbweN/IMG_4156.jpg?psid=1

 

[vi edit]

$50 for rolls of aluminum that I stamped myself into transfer plates

I'd like to know more about your stamped plates. I can see 2 different pex crimp/expansion systems, different plumbers? Please post your bill too as I would be interested to see that.

Two plumbers and an ambitious DIY homehowner actually. The plastic compression fittings are by the original plumber that did the house. The stainless crimp rings are from the guy that did the water heater, and the brass compression rings are from me.



As for the transfer plates, I got the idea from this site:
http://massiehouse.blogspot.com/2008/08/staple-up-radiant-heat.html

I made my own jig using some 3/4" plywood sleeper strips tacked down onto a sheet of plywood. Then took a big roll of aluminum flashing (see here: http://www.menards.com/main/buildin...ply-aluminum-roll-valley/p-1351567-c-5810.htm)

and cut it into 1'x1'x squares. Took the squares, set it on my jig, then took two 5/8" pieces of black iron pipe and stepped on them. The sleepers were set up to make two channels into the plate so that I could fit two loops per floor joist. I'll take a picture of that later tonight. I could cut the plates in half again to make a single channel, narrow run when I had to work around other spaces. Then I just took my pneumatic stapler and tacked them up.

Two rolls covered most of my staple up sections. Buying the plates premade would have cost 10x as much.

 

[Imp]

Insulated the basement floor slab? Lot of heatloss through there.

 

[roguerower]

Very nice setup. This is one of those things I'd like to install if I ever get a place of my own.

Is there a place where someone could see all the pictures of your house through all the stages of construction? I'd be interested in seeing it as it took shape.

 

[fstime]

So the gas hot water heaters are whats heating all that?

Doesn't it make more sense to use a gas boiler or maybe an instant water heater? I wouldn't think tank water heaters are built to heat water for a radiant heat system. Plus, they take forever to reheat water after all the hot water has been used up.

 

[vi edit]

So the gas hot water heaters are whats heating all that?

Doesn't it make more sense to use a gas boiler or maybe an instant water heater? I wouldn't think tank water heaters are built to heat water for a radiant heat system. Plus, they take forever to reheat water after all the hot water has been used up.

Actually they work incredibly well for my situation. Radiant systems don't really move an excessive amount of water. I think the total water amount is around 32 gallons + panel overhead. I've got a 40 gallon heater tank. Once the tank is up to temp (took about 6 hours to ramp up my system and get the heater caught up). At any given time I've got enough hot water to completely replace the entire system. But I rarely have to do that. Once the intial ramp up occurs it's a basic maintenance to keep water temps up. The loops under my main floor are only cycling about 6 total gallons through them. The basement loops are another 26'ish gallons worth and they don't turn on very often now that the slab is up to temp.

Now that I've got all of my floors up to temp the maintenance requirements are fairly low. The heater that controls these only kicks on every couple hours for about 5-10 minutes to heat the water back up. And it's not even needing to take it up that much. I've got it set at 120 degrees and the lowest I've ever seen the incoming water at was a little over 100.

With an on demand it would be running almost constant to keep things up to temp since my return loop is down about 20 degrees.

A boiler would be overkill for me. If I were doing the whole house and some snow melt systems for my driveway (which I'm kicking myself for not doing!) and the radiant was my primary and only means of heating then it would be worthwhile. For a system that is only running 3-4 months out of the year and is more for comfort and not being asked to provide insane levels of heat (150+ degrees) or high levels of recovery a conventional water heat works fine.

 

[fstime]

I see, thanks. Looks nice, let us know how much higher your gas bill is when it comes around.

 

[skyking]

In our case with the bathroom having it's own heating system, we will save money.
The house is 62 at night, then the forced air takes the whole house to 68, just to get ready to head out for work. Big KWH to do that.
The floor heat is 360 watts and I can play with the thermostat timing to get the air temp up to 68 in the bathroom by work time.
The floor heat thermostat is a dual function unit, measuring both air and floor temps.
No need to heat the rest of the house up just to go make a lunch and head out.

 

[vi edit]

Yeah this setup just works way different than forced air does. In my case I've an got 1800 sq/ft slab that is essentially one giant heat soak that is radiating heat up. Open a door up and it is barely a hiccup in the heat retention of the slab and it will bring the room back up to temp easily.

On my main floor I've got another 1000 sq/ft of porcelain tile that is acting as one giant radiating surface near every entry point in the home. Same concept...temp drops down and it's a lot less affected since it takes so much to drop the heat built up in the floor. I've got so little heat loss in my return loops that the upkeep from the heater is minimal.

The top floor is definitely cooler since the HVAC isn't running as much, but it's not significantly cooler. I can tell that the plaster walls upstairs are much colder to the touch than before but the air temp doesn't feel drastically different.

 

[Howard]

I'd love to put radiant heat into all the walls of my bathrooms. No more shivering during wintertime.

 

[iGas]

Heating bill will be cheaper than forced air, normally 20-40% cheaper heating bill with hydronic than forced air if you keep the forced air system and hydronic at the same comfort level.