Hot tub connection

[waterflea]

I'm about a day away from putting a match to my new system that I have been working on for over a year. She is full of water waiting for the electrician to finish
his part. A small part of all this is a feed off the primary loop that circulates through a heat exchanger to warm the "Hot Springs" hot tub. I have searched the site
looking for answers, not much luck. Has anyone connected their tub heater in tandem with their wood heat or is this just too complicated? Any ideas on how to
control these 2 heat sources.
Thanks.

 

[Nofossil]

I'm about a day away from putting a match to my new system that I have been working on for over a year. She is full of water waiting for the electrician to finish
his part. A small part of all this is a feed off the primary loop that circulates through a heat exchanger to warm the "Hot Springs" hot tub. I have searched the site
looking for answers, not much luck. Has anyone connected their tub heater in tandem with their wood heat or is this just too complicated? Any ideas on how to
control these 2 heat sources.
Thanks.

There are a few threads that discuss this. Basic idea is that you use a relay with a 220vac coil wired in place of the electric heating element in the hot tub. Use the relay contacts as if it were a thermostat, and plumb the hot tub HX like any other heating zone.

 

[dirtryder]

I'm about a day away from putting a match to my new system that I have been working on for over a year. She is full of water waiting for the electrician to finish
his part. A small part of all this is a feed off the primary loop that circulates through a heat exchanger to warm the "Hot Springs" hot tub. I have searched the site
looking for answers, not much luck. Has anyone connected their tub heater in tandem with their wood heat or is this just too complicated? Any ideas on how to
control these 2 heat sources.
Thanks.

Yes I did and it is awesome! It really was quite simple...I'll try to explain it but if you have any more questions feel free to PM me and if you have a fax I'm a pretty good at drawing..
I installed a water to water heat exchanger. The hot water coming in from the wood boiler is tied into a Taco 1" 3-way 24 volt valve. At rest, (no voltage) the boiler water "bypasses" the heat exchanger. I then interupted ONE leg of the 2 HOT legs to my heating element. My particular tub just cuts off the 110 volts to one leg. I ran this 110 leg to a 2 pole 2 position switch (on-off-on) which I installed in my side panel. In my "electric position" the wire just runs back to the original heating element and heats my water. In the "wood" position, when the tub thermostat calls for heat, it "energizes" a 24 volt transformer which in turn, opens the 3-way valve allowing boiler water to enter the heat exchanger and.....hot water! My tub has a 24/7 circulator pump which pumps through my heater and eventually returns to the tub via a 1" line to the tub. I installed the heat exchanger in the line directly BEFORE it enters the tub. In other words, the last thing that happens to the water returning to the tub is it gets heated. This prevents "any" flow issues when jets are running, and also does not interfere with temp sensors since I heat my water "after" them. The "only" down fall (if you want to call it that) is when I have the tub set for 102 degrees, sometimes it may climb to 103 with residual heat in exchanger.......but I can live with that since I'm getting the heat for free......I installed by-pass valves and line to bypass the heat exchanger if need be.
Works like a charm.

Oh BTW, I installed ground fault breakers in my panel that feed my circulating pumps from my OWB (2....one for house/ hot tub loop, one for my garage loop) the reason being, if by some chance, some how, your boiler water becomes (energized) by a circ pump, then your tub exchanger "could" become "energized" leading to the tub becoming "energized" and if your in the tub.........might be overkill but theoretically it can happen so the ground fault breakers should eliminate the potential scenario...