What should I set my electric boiler temp at?

[Rusty Bumper]

I heat a 26'x48' garage with 14' sidewalls here in Minnesota. I usually keep the temp around 45-50*F through the winter and bump it up to 65 or so the day before I plan on working in there.
The boiler heats the in floor pex system set up for 6 zones but I have all five wide open as it is one large space. (lesson learned on the expensive zone manifold purchase)
The 9000 watt electric boiler is set up for load management heating w/ the electric company. The circulation pump turns on/off through the boiler control board. (my brother says he continuously runs his pump all winter long)

I would like to know what temp I should set my boiler at. I have a range of 90 to 160*F. I currently have it set at 140 and not really sure how/why I came up with that setting.
Attached are pics of the boiler tag, the heat control and the pump.

 

[finn]

I was always told that 100-110 is the max water temperature for in slab pex tubing systems. Staple up (house wood floor) can run hotter.

My shop system is set for 104 degrees.,

 

[79firebird]

My grandparents in floor system in all 3 houses they have had built over the years were set to 110

 

[Rusty Bumper]

Hmm..

 

[Dagny]

100 should do it.

 

[Jackfre]

To high a temp can actually damage the slab. 100-110 and see how it does. It will not recover quickly. For a water boiler return water temps are an issue as they can cause condensation and deterioration of the boiler. That should not be a problem with an electric

 

[6768rogues]

Hotter costs more money. Cooler might not provide adequate heat. I would start at a reasonable temperature and see how it goes. If the building is cold and the pump runs continuously, raise the temp. If the pump only runs occasionally, lower it. With some experience you will be able to predict the temp needed depending on the weather forecast.
At the school where I worked, boiler temperatures were computer controlled based on outdoor temperature sensors.

 

[Chris705]

Do you use a mixing valve to mix hot Supply with cooler return?
Can you post photos of your whole system ?

 

[Rusty Bumper]

No mixing valve as it is a closed loop system. Pretty standard system. Here is a pic....

 

[LS6 Tommy]

I wouldn't set it much over 110° F.

Tommy

 

[Rusty Bumper]

OK, so I have temperature gauges monitoring the temp going into the slab. I'll set the boiler @ 110 and watch the gauges.
I appreciate all the replies, advice, and experiences. I am going to put in a call to my furnace guy. and maybe my slab contractor as well.
Rusty

 

[Chris705]

Rusty - I agree with the others that 110 is about where I'd set your temperature. Curious on where/how you feed the boiler make up water? As the air gets purged out of the water you tend to loose volume and need a way (maybe short term) to make up that volume with new water.....I don't see a water feed/pressure regulator on your setup? I vaguely am aware of other folks having electric boilers running into problems because of low water and burning up elements/internals.....just be cautious here....

 

[Rusty Bumper]

Rusty - I agree with the others that 110 is about where I'd set your temperature. Curious on where/how you feed the boiler make up water? There is a one way valve that a garden hose hooks up to located on the top manifold all the way to the right side. Difficult to see unless you zoom in on the picture. As the air gets purged out of the water you tend to loose volume and need a way (maybe short term) to make up that volume with new water.....I don't see a water feed/pressure regulator on your setup? There are two pressure gauges on the system, not visible, on the inlet and outlet of the boiler, monitored regularly. There is also a Honeywell air eliminator at the top of the expansion tank. I vaguely am aware of other folks having electric boilers running into problems because of low water and burning up elements/internals.....just be cautious here....

Responses in red above.
I now have the boiler set @ 110 and after 2 hrs there is 72* water going in and 50* water coming out of the slab. I'll check it again after a while.

 

[Rusty Bumper]

After speaking w/ my furnace guy he said these "mini boilers" should be set at 110 or 120 max. He even verified it w/his technician who was in the office today. He mentioned the larger house boilers are set higher.
My water temp was up to 85 going into the slab after about 4 hrs.
Thank you again everyone.
Rusty

 

[Chris705]

Enjoy your warm comfortable garage!!!