Electric Boiler Set to Heat only when Thermostat Calls
We have an electric boiler in our shop. We keep the thermostat at 10c all winter. When we moved here we had a hvac company come look at it and they suggested setting it up to only turn the boiler on when the thermostat called for heat. So basically the boiler never heats unless the thermostat turns it on. It always comes on at stage 3 heat. Heats water a bit until thermostat is satisfied then turns off completely until next call for heat.
They suggested that this would save us money as we keep it fairly cool out there and electricity is expensive. Does this make any sense? It appears the boiler has 3 stages of heating. With the current setup it's always maxed out when it runs. Would it be anymore efficient to let it heat water continually and then the thermostat just triggers the pumps? This is how it was setup before.
I've attached pics of the setup. Thanks.
Comments
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Electric boilers are not like fuel burners. No matter the output they are pretty much 100% efficient. If they need to deliver a certain BTU to the building to keep it at 10C, doesn't matter how you run it, it will use exactly the same kWh. The heating elements will last longer if they are run at lower power though.
Where you can play with settings is if you are in a place with TOU electric rates. There it would make sense to only run the boiler when electricity is cheap and coast through the expensive parts of the day.
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The space requires a given quantity of BTUs to maintain a given indoor temp. With electric, that BTU quantity is directly relative to the cost. There would be no savings by converting to a hot start setup; probably the opposite actually.
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The only savings might be in standby losses when the building is unoccupied.
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The pump at the boiler should be turned down so the motor is horizontal. Are there zones?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
There's two pumps. One for the infloor and one for the baseboard heaters. They both run when there's a call for heat.
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I can't see enough of the plumbing, is there a temperature mixing valve for the radiant? What temperature does the boiler run?
I know some versions of that boiler have Outdoor Reset control on board, that could be a nice feature to use if the boiler is running up to 180°F?
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
He’s referring to the mounting position of the pump. It has to be mounted with the motor horizontal, not vertical. It will fail prematurely like that.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.1 -
Here's a few more photos. There is a mixing valve. Boiler appears to be set to 180f. The pumps have likely been setup like this for many years. I looked in the manual and I don't see any mention of odr. I attached the manual as well.
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Turning the boiler down to the appropriate temp and getting rid of the mixing valve altogether would net you the highest overall efficiency, which would also be a great time to rotate the one circ to horizontal.
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Unless you have a lot of BB or a high temperature staple up? I'm not sure you could run a single temperature system when fin tube and radiant mix.
Get them with 10- 12° of one another and it could work.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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