Anyone tried using forced hot water funance as heat source to HLT?

[CapeHound]

Has anyone tried using a circuit on a forced hot water furnace as a heat source to a HTL? The idea is to add a new circuit to the furnace and run it through a heat exchanger in the HTL.

Pros: High capacity 180 degree water, efficient, responds to a thermostat or switch, off the shelf parts (including the recirculating pump) and it's already in my basement.

Cons: Wife thinks I'm nuts.

 

[audger]

any source of heat can be used. ive actually been looking at regular hot water heaters to use as a HLT. where theres a will, theres a way!

 

[Hanksv]

What do you mean by "forced hot water furnace?" Are you referring to a boiler for hydronic or radiant heat? The kind of system that circulates hot water through radiators or in-floor tubing to heat your home? If so, your idea is pretty much the same as an indirect hot water tank that is commonly used for domestic hot water supplies in these kinds of heating systems. Basically, the boiler water circulates through a coil inside of a water tank. The coil keeps the boiler water separate from the clean domestic water. It is kind of like an immersion chiller in reverse - the coil heats the surrounding water. The hot water that is in the tank runs through a mixing valve before entering the domestic water circuits so that it gets mixed down to 105 to 110 degrees. I installed this type of system in my house. My hot water tank stores water at 145 degrees and is mixed down to 105 for domestic uses. I installed a drain valve before the mixing valve, so I have a supply of 145 degree water on demand if I need it. I put the valve there so I can drain the system, but I have to start using it for brewing. I hadn't thought of that until I read this post!

 

[CapeHound]

Yes, boiler is probably a more accurate term. The idea is to simply add a new zone that runs through a heat exchanging in the HLT. It's already circulating a lot of 180 degree water around the house.

 

[sjwelna]

In daydreams of scale-up for my brewing, I was thinking it would be awesome to just utilize a 60 gallon hot water heater as a HLT with a huge heat exchanger coil in it.

-Steve

 

[Hanksv]

You could total do this depending on how your zones are currently set up. Keeping everything safe is the important part. A couple concerns. First, if you screw up the plumbing and air gets trapped in your boiler, you could create steam, steam creates too much pressure, too much pressure causes your boiler to explode and take your house with it (assuming cast iron boiler, no pressure relief, no temp/low water shutoff, etc). Second, 180 degree water will scald you on contact. Make sure all connections are solid and all valves and drains are safe.


If my name was Bubba I would tap into a supply and return line with 1/2" ball valves and run 1/2 oxygen barrier pex to a big coil of copper in an HLT. Open the valves and turn your thermostat up whenever you want hot water.

 

[JoeDirte]

I toured a small brewer in town and they were using two hot water heaters as HLT's. They had to override the safety features and used temp controllers on them. They also added a recirc pump to run between them to keep the water at the same temp throughout the height of the tank.