OWB to Spa connection

[zpgpmn]

Hello! First post.
I am nearing the end of my OWB install and I am wondering how to connect this to my spa

I bought a 85,000 BTU Stainless Steel Heat Exchanger w/Opposite Side Ports
Port sizes: (to/from Boiler) 3/4" - (to/from Pool) 1"
Looks like the incoming waterline to the Spa's electric heat exchanger is a 2" line and I have 1" thermopex.
This is going to use the same line after it goes through my Furnace's heat exchanger.
Any ideas how this is going to work? Do I need a thermostatic valve in there? I know I want to make sure the tub doesnt heat up past ~180 degrees.

 

[Highbeam]

As a fellow hot tubber, I've always wondered how people do this. The tub pump will run on a schedule to filter the water but the heating element only fires when the thermostat in the tub calls for heat. If you trigger a zone valve to run boiler water through the HE only when the tub is below setpoint then you should be able to prevent overtemping the spa. Look to the area on the right of the OEM heater for a location to splice in your new HE. That pump is blowing into the side of the OEM heater.

 

[maple1]

I haven't hooked a hot tub up before, but I'm thinking another controller might help or be needed (a Johnson A419 should work), that would start up the tub pump and also at the same time open a zone valve on the zone going to the HE. With the zone valve end switch in turn starting your zone circ. All done, when the controller senses a temp drop below setpoint. Which would assumedly be just a little bit above the setpoint on the factory hot tub thermostat. Or, you could maybe hijack the existing heater control, to operate said zone valve - but that would disable your electric heater. If the wood will be the primary heat source from now on, you could maybe do that and use a new controller just on the existing electric heater heater. That may be easier overall.

Not sure how the pump is controlled under normal operation or how to tap into it with the new controller but there should be a way?

Not much space to work with under there though - and that short big pipe would be a bear to splice into by the look of it. That kind of looks like the same kind of pipe you would use for a suction hose on a 2" water pump, and that stuff is gnarly stiff and a PITA to get fittings into - usually requiring disassembly by cutting apart. Splicing in won't be easy at all - but it should go where Highbeam said. That looks so ugly - I might be tempted to try T'ing into one of the other smaller lines there, somehow?

 

[Highbeam]

One of the members here with a rather extensive computer monitoring setup and a website detailing his systems has a hot tub heated by his wood boiler. I forget which member it is but he will surely come around and let us all know. Hot tubbers are an enthusiastic bunch!

 

[TCaldwell]

Whatever signal controlls the current heater should be able with possibly a relay if needed to control a Johnson A419 as maple says. not sure if the temp signal also controlls the tub pump or the pump runs on a schedule dictated by the filter time, morning and night. These questions should be answered by the existing control package.

 

[goosegunner]

I have a pool heated with a similar heat exchanger. The one thing that you should plan on is a flow switch that will not let the boiler circulator send water to the exchanger if the spa pump is not running. It will soften your pvc, no need to ask me how I know.

gg

 

[huffdawg]

One of the members here with a rather extensive computer monitoring setup and a website detailing his systems has a hot tub heated by his wood boiler. I forget which member it is but he will surely come around and let us all know. Hot tubbers are an enthusiastic bunch!

NoFossil

 

[Highbeam]

NoFossil

I can't seem to find him on the member list. It sounds familiar. Is his exact member name spelled differently? Trying to page him...

Here's his site with the hot tub and monitoring stuff:

http://www.nofossil.org/

 

[Fred61]

He's the author of the last entry in the stickeys. click on his name.

 

[zpgpmn]

Heck yeah! Thanks everybody for your replies. This is definitely not as straight forward as I thought. I'm in over my head. I've hit the cap of my budget for this year so this is going to have to happen next year. I got a lot of research to do! Thanks again

 

[goosegunner]

One more thing to consider, Is your hot tub outside?

If yes, what are you going to do for freeze control for boiler lines going to hot tub?

If tub doesn't call for heat or flow switch fails the boiler lines could possibly freeze if no method is in place to protect them.

 

[zbgpmn]

Gg: yes outside, I have a thermopex line running to the tub but have not yet drilled the hole to enter the the access panel.

 

[huffdawg]

I can't seem to find him on the member list. It sounds familiar. Is his exact member name spelled differently? Trying to page him...

Here's his site with the hot tub and monitoring stuff:

http://www.nofossil.org/

http://www.vecs.org/

 

[goosegunner]

Gg: yes outside, I have a thermopex line running to the tub but have not yet drilled the hole to enter the the access panel.

Is it below the frost line and then into the tub?

If not I would think that you will need to think about freeze protection.

 

[zbgpmn]

Is it below the frost line and then into the tub?

If not I would think that you will need to think about freeze protection.

It's above ground but thermopex insulated until it enters the hot tub access panel. The hot tub sits on a deck with a crawl space underneath. Unfortunately I cant dig there.

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