Hot Tub Conversion

Big Dog Dan

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

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

BCConstruction

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

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

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

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.

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Big Dog Dan

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.

Big Dog Dan

Well
I built the system by cutting a hole in the side of an old boiler. I mounted the boiler upside down on top of a wood stove last fall.
I inserted a hot water coil in the old boiler and used gasket material to seal the tank less coil to it. Had to tap threads in the boiler to hold the coil with heavy torque.
The wood stove sits under a boiler I picked up from a job.
I also have the old boiler that sits on a wood stove (the wood stove also has a large whole cut out of it where the old boiler is placed in direct path of the fire.)piped to my house boiler which is also connected to my baseboard heaters.
I really have a wood burning/oil fired combination. What is good about this system is that instead of having a wood fired boiler outside in the yard, I have it inside in my basement where all the heat is going in the pipes. The excess heat from the wood stove also heats the basement and house. Basically I get all the heat. The system sits in a 10' concrete section of my basement, so it is surrounded by concrete walls. (real safe for wood/oil boiler set up.

Warning! This thing ain't pretty, but it works.

Had some real experience with the system freezing.
I drained the tub to clean it,and filled it again with hot water. Well in the middle of the night I work up and was outside with my B tank torchin the pipes for two hours while everyone else was sound asleep.
That was real fun
Try not to burn the pvc/poly pipes and do it fast enough to thaw out the pipes.
I used pex as the supply to the hot tub underground about 4' deep and almost 20' from the house.
Photos when I get a chance.

Big Dog Dan

The system is working. Hot water from 4 ft. below ground circulates from my boiler,
and also adds a 350 gal. of storage water.
I used a tempering valve to control the temperature and I
can use wood or oil to heat with while the hot tub stays at 101 and
has independent loop.

rex

id hope that you heat with wood most of the time!

thats awesome good job

Big Dog Dan

thanks Rex
I use both. As the wood stove starts to burn down, the oil fired boiler just comes on by the temp sensor built into the boiler.
It was fun to turn it on just as winter hit.
The electric heater that comes with hot tubs are too expensive to run all year round.