Hot tub conversion - Contractor Talk - Professional Construction and Remodeling Forum

Big Dog Dan · 09-06-2009, 07:19 AM

Hi all can anyone give me advice on plumbing my outdoor hot tub to a zone from the boiler?
I have installed a separate zone with a 007 ready to hook up to my superstore, but I was not sure how I could control the temperature cut in/off for the circulation pump to come on.
Maybe I could use the hot tub temperature sensor. It uses electricity to heat the water. Problem is the sensor seems to of failed in the control panel.
Can I put an aquastat relay somewhere that would sense the water temperature? I was thinking of just imbeding the aquastat prob in the tub inside the control door where the pump/pipes are located.
I'm putting the pipes under ground to the tub from the super store in the basement. The system must keep the water in the tub around 102 degrees in below freezing weather.

Big Dog Dan · 09-07-2009, 01:27 PM

Guess no one has done this.
When I get it done I will post how it works
Thanks

BCConstruction · 09-07-2009, 02:38 PM

Be the first time i ever heard of a hottub using an external source for heating. Be nice to see some pics though. New to me i tell ya.

thom · 09-07-2009, 05:57 PM

I use a tankless gas water heater to heat my spa. Works fine.

You want to do something completely different, may not work. Making this a zone on an existing heating system will result in mixing of the spa and heating water. I don't know if that will screw with your system or not. If that works for you, the next issue is pressure. If the heating system is a pressurized system, I don't think you can make this work because the spa is obviously non-pressurized.

The spa pump will pump far more than you can put through the boiler. That means you can only pump some of the water through the boiler then mix that back into the return water stream. Getting this set right is a challenge. You must provide adequate flow and pressure to fire the boiler without over-restricting the flow from the spa pump. In your case, you will be dealing with both the spa pump and the circulating pump so it will be even more difficult.

As for the control for the zone valve, that is pretty easy. You can get a bulb type sensor on a thermostat. The sensor inserts into the pipe through a threaded fitting, generally in a "T". That would open the zone valve and turn on the circulation pump for the heating system.

BCConstruction · 09-07-2009, 06:23 PM

Quote:

Originally Posted by thom

I use a tankless gas water heater to heat my spa. Works fine.

You want to do something completely different, may not work. Making this a zone on an existing heating system will result in mixing of the spa and heating water. I don't know if that will screw with your system or not. If that works for you, the next issue is pressure. If the heating system is a pressurized system, I don't think you can make this work because the spa is obviously non-pressurized.

The spa pump will pump far more than you can put through the boiler. That means you can only pump some of the water through the boiler then mix that back into the return water stream. Getting this set right is a challenge. You must provide adequate flow and pressure to fire the boiler without over-restricting the flow from the spa pump. In your case, you will be dealing with both the spa pump and the circulating pump so it will be even more difficult.

As for the control for the zone valve, that is pretty easy. You can get a bulb type sensor on a thermostat. The sensor inserts into the pipe through a threaded fitting, generally in a "T". That would open the zone valve and turn on the circulation pump for the heating system.

Yeah you def wouldnt want to run your water from the primary heating system through the hot tub as an extra zone. You could if you run it trough a heat exchanger which is what i guess it is already doing? Never seen one but im interested to see how they work.

I see this the other day though. Seems like an expsensive way to heat pool water to me lol

nadtwins · 09-08-2009, 10:04 AM

In short what you would need to do is get a separate liquid to liquid heat exchanger to plumb your boiler and spa to. You would never want to plumb your spa directly to your boiler with out going through an exchanger, if your water chemistry is off you could destroy your boiler in a few days!!
As far as controlling the temperature you would install a aquast – thermostat for that zone with a really to control a separate circulation pump. You would also add a freeze control as far away from the spa as possible. This is a very simple expatiation on how to accomplish your goal.

Big Dog Dan · 09-08-2009, 05:57 PM

Hello
Thanks for the comments.
I am planning to use a heat exchanger as I said,and I plan on removing the spa circulator. Not the high powered air/water jet pump.
Problem is I am so busy I can not stop to do this simple job for myself.
As suggested and advised I will use a aquastate.

I was not planning to use boiler water directly.
I will post detail if I can just find some time to finish this. I have the 1" zone installed on the boiler with a 1" swt shut off and flange ready now.