Plumbing pool pump to wood stove furnace


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Old 06-05-19, 03:44 PM
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Plumbing pool pump to wood stove furnace

I have an existing pool pump setup that consists of 1-1/2 flexible pvc and some valves and elbows going from the pump to the filer and then the return lines.

I recently acquired an old wood fired furnace so I basically have a wood stove with a 75 stainless coil which enters and exits the stove with 3/4 threaded pipe.

My question is, if I install a 1-1/2 3-way diverter valve in the line after the pump, how can I connect the 1-1/2 pvc to the 3/4 thread on the stove sitting outside my shed? It would be similar for the return.

Any help is appreciated
 
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Old 06-05-19, 06:30 PM
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I drew you a diagram as I would personally make the connections.

You can't have all the water from the pump go thru the heater. The flow needs to be reduced down. When valve A is open the bulk of the water goes directly to the pool. The B valves are for flow thru the heater. That part is experimental. You may be able to leave them all the way open with A all the way open. Some water will flow thru the coil. As you close A..... more water flows thru the heater. You can use the valves to setup the flow thru the heater. When the heater is not in use..... valve A is open and the two B valves are closed. It's important to keep the water moving from the pump to the pool with little to no reduction. I would never recommend closing the A valve completely.

You can get all kinds of PVC fittings. I'd use three 1-1/2" PVC ball valves. Then reduce the PVC down to 3/4" right after the valves. Some gauges would be cool to help set the valves.

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Old 06-06-19, 04:21 AM
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I would caution against putting shutoff valves on the lines leading to the wood stove. That is asking for a steam explosion. It is just too dangerous unless you also include something like a temperature and pressure relief valve of sufficient size in the heater loop.

When I was a child my father made something similar and he ran the full output of the pump through the heater. Looking back I'm sure the resistance of all the piping and 90 degree bends hurt filtration but all that resistance also slowed the flow so the water entering the pool was quite warm. With 75' of 3/4" in the heater you'll have considerable flow resistance so I'm not sure you'll need to do any throttling down of the flow. All the piping will do that naturally. You will definetely want a way to bypass the heater when not using it because you won't have good filtration when using the heater.

How far is the wood heater away from the pool? You'll want to insulate the lines if it's much distance.
 
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Old 06-06-19, 05:16 AM
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Thank you @PjMax for the diagram. I think Ill go that route with the A ball valve and the B as well. Im wondering if I should leave out the second B valve downstream just to rule out any possibility of trapping water in the coil. It would still allow me to shut off the coil during normal filter operation and also open it fully when heating.

Lastly, would any big box store or Hardware store have a way to go from 3/4 thread to some form of pvc?

Thank you both for the ideas and suggestions.
 
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Old 06-06-19, 07:41 AM
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Yes, leaving out one of the ball valves is a good idea for safety. And "yes" most big box home centers and plumbing suppliers will have fittings to make the transitions. Just not whether you will need male or female. If they don't have one fitting to make the transition then you can stack two fittings to get you there.
 
 

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