WHAT IS MOST EFFICIENT WAY TO HEAT HYDRONIC RADIANT SYSTEM

[SRSTUDIO]

Hi,

I am building my 1800 sqft studio on 4" slab and plan to use hydronic radiant heat system installed in slab.
What is the best way to heat the water.
I'd prefer not to use electric and found some fantastic hi efficiency wood boilers (92% MBTEK PEllet DUO is my favorite so far) however after doing many calculations, factoring in time, maintenace etc I am wondering at the true cost. Does anyone have any experience with this and going down this road? wood or electric best for this system. I know there are very efficient and require a low running temp which is why electric might not be insane, most efficient. You are pegged to the price, but then again its all connected, cord wood going way up.
Any experience and feedback greatly appreciated

 

[salecker]

One reason for going with wood is the savings of supplying your own

 

[SRSTUDIO]

right, I have a woodshop, but we probably only produce 80 gallons of premium kiln dried wood waste a month. Which would mean I would need to purchase cord wood, at 350 a cord where i live in Maine I am not sure if this will come out cheaper than, say electric?

 

[EbS-P]

Well… I see radiant floor as a big splurge. So go big.
Heatpump.

 

[salecker]

right, I have a woodshop, but we probably only produce 80 gallons of premium kiln dried wood waste a month. Which would mean I would need to purchase cord wood, at 350 a cord where i live in Maine I am not sure if this will come out cheaper than, say electric?

I would say that if you don't have the ability to get your own wood then you definitely need to crunch the numbers.
If you are buying wood it can get expensive, but having a wood burner means you can always find something to use for heat.
You may not always be able to get pellets, oil, or propane. But there will always be wood around to burn

 

[EbS-P]

Make sure you insulate under that slab!

 

[mark cline]

I put 2” of polyisocyurnate foam board under my slab. Wish I would have gone with 4” , maybe overkill but it was fairly inexpensive. Also use a heavy plastic sheet under the foam board.

 

[Highbeam]

You are asking about efficiency but I think you mean to ask what is cheapest. Straight electric is 100% efficient, you’ll never get that with wood or pellets.

To find out what’s cheapest you need to know both the efficiency of the heater as well as the cost of the fuel.

A straight electric boiler is so cheap, simple, and dependable that you should install one as a backup if not the primary.

 

[bigealta]

You are asking about efficiency but I think you mean to ask what is cheapest. Straight electric is 100% efficient, you’ll never get that with wood or pellets.

To find out what’s cheapest you need to know both the efficiency of the heater as well as the cost of the fuel.

A straight electric boiler is so cheap, simple, and dependable that you should install one as a backup if not the primary.

So what do you use? just an electric water heater. Or a specific electric boiler?
I'm seeing boilers starting at $3k for the smallest ones?

 

[Highbeam]

So what do you use? just an electric water heater. Or a specific electric boiler?
I'm seeing boilers starting at $3k for the smallest ones?

I’m at the same stage you are. Tubes in the floor, insulation done. Everything is very expensive so researching. There are lots of electric boilers much cheaper than 3k usd. Fuel cost can be high though.

 

[chew72]

I'm an electrician and have wired for infloor heat, hot water tanks, 30KW electric boilers and even made my own electric heater pictured below. A standard hot water tank can have a larger feed ran to it, or a second feed ran and be rewired to operate both elements at the same time, doubling it's output. Other than space and maybe a small amount of extra heat loss, I haven't found theres much of a difference between a hot water tank and electric boiler if their output is similar.

If I recall the homemade heater is 1" iron pipe with two tee's. A thermowell in the top tee, the bottom tee retapped to straight thread for a standard electric heater. It was for the infloor heat of 1 room before I installed the boiler system. Going forward it will be freeze protection of our straight water system if we are away and not here to make a fire for an extended period.

 

[brenndatomu]

A straight electric boiler is so cheap, simple, and dependable that you should install one as a backup if not the primary

Maybe cheap to buy, certainly not to operate! Its the most expensive option to operate...but still a good "backup" option to keep the bank/ins. co. happy.

 

[Highbeam]

Maybe cheap to buy, certainly not to operate! Its the most expensive option to operate...but still a good "backup" option to keep the bank/ins. co. happy.

That depends on your fuel cost. Some places have very cheap electricity and of course some folks also have solar and need to blow a surplus on their account every year.

Kinda like the guy fueling a wood boiler with supermarket firewood bundles in New York City. You must consider your fuel cost, efficiency, and equipment cost. That’s why these decisions are so hard.

These days, minisplit heat pumps are very hard to beat.

 

[peakbagger]

Once air to water heat pumps get more popular in the US, they are going to be hard to beat for radiant applications as long as the tubing design is sized for low temperatures. With a potential for a $8,500 rebate for household heating coming soon, it is going to be a no brainer for radiant installations.

 

[brenndatomu]

That depends on your fuel cost.

Yes and no...the only way it'll be cheap is if you are blowing off solar credits, as you mentioned...we have fairly cheap power here, but electric heat is still not reasonable to run, not even a little bit. Not including heat pumps, I was commenting on the electric boiler...

 

[blades]

i do not consider electric to be inexpensive. Perhaps the base cost but then there are more add-ons to that base ( at least in my parts). if you have electric to home and can run a line from there to shop maybe but if is going to require separate meter there is a monthly fee just for it + all the other add-ons.
The take away for a wood heat system and in floor heat is you are going to need a large storage system of hot water to keep the floor at x temp if/when the wood dies out. Takes along time to get that slab up to temp , maintaining temp is the key to comfort.

 

[Highbeam]

Yes and no...the only way it'll be cheap is if you are blowing off solar credits, as you mentioned...we have fairly cheap power here, but electric heat is still not reasonable to run, not even a little bit. Not including heat pumps, I was commenting on the electric boiler...

A lot of residential has been and is still being built with electric baseboard heat, wall heaters, or straight electric furnaces. Same efficiency as an electric boiler. You might be surprised just how cheap it is compared to buying market rate firewood in some areas after you apply the efficiency penalty of a wood boiler plus the insane installation price of a modern wood boiler with storage. That’s even before considering the labor cost of daily fires and maintenance.

 

[brenndatomu]

You might be surprised just how cheap

Nope...my buddy had electric radiant heat in his well built brick home...$900/mo in January, set to 68* daytime...I'd say almost anything else wins long term...and again, power prices here are very reasonable (non profit community owned power plant).

buying market rate firewood in some areas after you apply the efficiency penalty of a wood boiler plus the insane installation price of a modern wood boiler with storage.

I dunno how people can afford to have someone else do everything for them...I know I certainly can't!