Overheat loop basic

[maplewoodshelby]

I'm installing a new wood boiler as an add-on to my existing propane boiler. I plan un using the wood boiler for most heating and dhw. I've got a fellow helping that has good plumbing knowledge and has fooled with propane boilers in the past. However, we are a bit stumped on how to do the overheat loop (in case of power failure or just plain overheat) or if I need it. The manual for the new wood boiler says that overheat loop should be used for all installs but tha is basically all it says. I have a three story house and my boiler sits about middlle elevation of all of the baseboard heaters in a room off of the garage. There is about a 15 ft run of pipe leaving the boiler before it goes up into the house to heat the baseboards.
My question is do i need an overheat loop because there are many baseboard heaters above the boiler location and thus thermosiphoning can occur
If I do need the overheat loop exactly how do i plumb that in to the system. Seems like it would function just like the baseboards and always be drawing hot water thru it

Thanks

Sammy

 

[flyingcow]

I drive truck for a living, so take my "info" with a grain of salt. But basically, if the zone valves will open when the power goes out, you should be all set. Providing the baseboard is above the elevation of the boiler. Don't forget the pressure relief valve and should be all set. BUT now that i probably misinformed you, the experts will chime in and correct it. I know I missed something. What do you have for a boiler? Might be useful info.

 

[maplewoodshelby]

I have an Energy King 450 EKB. Its about 160000 BTu. To clarify a bit. Some of the baseboards are below and some are above the boiler. With the first section of pipe leaving the boiler at the same level for about 15 feet before it goes up to the first baseboard

 

[Gooserider]

It may be one of those "try it and see" situations - that 15 feet of level piping is possibly a problem in that it might act as a heat trap to keep you from thermosiphoning, or it might not be an issue. How do the two pipes run - especially when the hot pipe comes out of the boiler top does it just make a 90* bend and run level to the house baseboards, or does it drop down to the bottom of the boiler and run along side the cold pipe?

I would suspect that optimal would be for the hot pipe to run to the house at the boiler top height or above, and ideally even angle up a bit, while the return pipe is at the floor level... Next best would be for both pipes to be up high, with the return dropping down as it gets to the boiler. I would be afraid that if the hot pipe dropped down considerably before the house run, it would act as a heat trap and keep the convection loop from starting.

To test it, hook up everything and get a good hot fire going, and everything up to temperature, then pull the plug on the system while watching the temps and pressure guage - if you start overheating, or the pressure goes to high, restore the power to finish the burn and install a loop. If the readings stay OK and you appear to have circulation while the fire burns out, you should be all set.

Gooserider