Garn and Electric Backup

[Como]

I have just been told something that makes no sense to me.

That the electrical elements are just there to be able to provide freeze prevention. Not as a backup.

9 elements strike me as being able to do a bit more than that.

Anyway just wondered what people who have them are doing?

 

[TCaldwell]

I was told that the elements are a actual heat supply source, and were optionally offered because in certain areas of the country off peak electricity at one time was a viable alternative, however they and other options would provide freeze protection. it takes a lot of neglect to freeze a insulated garn inside a bldg.

 

[Jim K in PA]

David - Dectra sells an electrical control panel to supply power to three of the nine elements at one time, and it rotates the output across all of the elements in a sequence. As Tom said, the intent of the electric option was not for freeze protection, but to take advantage of substantial off-peak rate discounts to SUPPLEMENT the heat input. I, and others, have incorporated an electrical "backup" as a last ditch freeze prevention exercise. I have a single element connected to power with a DWH surface control, but doubt it will ever be needed. I used the element to raise the temp of the water before my first firing, and it has not been energized since.

 

[Como]

Many thanks.

Why would you want to rotate the supply between the elements?

I can see putting one in for last ditch protection, I was also thinking of using a Solar HW panel to do something similar.

We can get off peak electricity, cheaper than Propane. I was more thinking of keeping the system running at a lower level when we are not there, keep the building above freezing. I am coming more to the conclusion that propane might be a better choice.

 

[Jim K in PA]

Many thanks.

Why would you want to rotate the supply between the elements?

To extend the life of the elements. Given the amount of heat energy the GARN can absorb, you could run three of them for many hours. The amperage draw is subtantial, and rotating the groups prevents deterioration of one set. To change an element requires draining the tank - not something I would want to do unless I had no choice.

I can see putting one in for last ditch protection, I was also thinking of using a Solar HW panel to do something similar.

Check the output of the panel. Unless you have a BIG panel, or lots of them, Solar HW will not likely add much useable heat to the tank, and during winter will not be much of a backup.

We can get off peak electricity, cheaper than Propane. I was more thinking of keeping the system running at a lower level when we are not there, keep the building above freezing. I am coming more to the conclusion that propane might be a better choice.

I agree. I will be incorporating a propane fired backup into my GARN side plumbing for heat demand and tank protection if/when we are not around to fire the unit during the winter. I will be using a 150k Btuh pool heater.

 

[Como]

Many thanks, makes a lot of sense.

The solar should put in about 300,000 btus a day in winter, it's main purpose is hot water for the summer. We have lots of sun, cold is the killer.