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...