Domestic from Boiler Water ??

Domestic from Boiler Water ??

PostBy: traderfjp On: Tue Jun 10, 2008 8:30 am

I have a coil in my stove that runs into a 30 gallon storage tank and then into my boiler and it makes a big loop. The coil has 40' of pipe in the loop. The stove's coil does a great job of heating the basement. I would love to steal some domestic off the storage tank in the system. Is there anyway I can do this? RIght ow I have a oile fired how water heater and would love to shut it down in the winter. I also have a filter on my water supply so any sediment would be filtered out and we use bottled drinking water anyway.

Thanks in advance.
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Re: Domestic from Boiler Water ??

PostBy: billw On: Tue Jun 10, 2008 9:04 am

Are you talking about using the boiler water directly for DHW or using the boiler water to heat the DHW?
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Re: Domestic from Boiler Water ??

PostBy: traderfjp On: Tue Jun 10, 2008 10:21 am

I'm talking about using boiler water for domestic. Is there anyway to do this?
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Re: Domestic from Boiler Water ??

PostBy: LsFarm On: Tue Jun 10, 2008 10:31 am

Quick answer is don't do it .. you will have a constant supply of fresh oxygen-rich water going through the boiler,, which will promote corrosion in the boiler. If you want to use the boiler water, purchase a water-to-water heat exchanger and use it to heat your domestic hot water, or buy an indirect hot water heater for your DHW..

A boiler is an expensive item made from carbon steel. It will corrode quickly with oxygen rich fresh water running through it.. The sealed,and recirculating hot water in the boiler and piping depletes it's existing oxygen then the water is benign.

I use water to water heat exchangers to transfer all my boiler heat into my heated shop floor, and into my home's baseboard/propane boiler system.. the water systems do not mix.. only exchange heat at the water/water plate exchanger.

Greg L
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Re: Domestic from Boiler Water ??

PostBy: billw On: Tue Jun 10, 2008 10:34 am

From what I learned here water in a boiler for any length of time becomes 'dead'. It loses it's oxygen. That keeps the boiler from corroding. Replacing the dead water with fresh seems like it would make the boiler corrode faster. It might be a better idea to connect an indirect water heater to the boiler and heat your water that way. It's more expensive but I think it would be better for your system in the long run. I'm just an amateur I'm sure some of the plumber types can give you better info.

Richard has a diagram of how to use a hot water heater and the DHW coil to make hot water using gravity and a couple of flow check valves. I thought it was in the knowledge base. I just checked and didn't see it. If your interested ask him.
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Re: Domestic from Boiler Water ??

PostBy: traderfjp On: Tue Jun 10, 2008 10:52 am

I have coils in my boiler and could create a loop with my oil fired hot water heater. In other words the water from my HW heater would circulate through the coils in the boiler. The only problem with that is the boiler's temp rarely goes above 140. I've turned the aquastat all the way down on the boiler and use the hot water from the stove's coil to make heat for my basement.
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Re: Domestic from Boiler Water ??

PostBy: Richard S. On: Tue Jun 10, 2008 1:25 pm

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