Is schedule 80 & check valve needed?

[plucky71]

Hello,
I was given a used pool heater that I am hooking up to my pool. I have two questions. Do I need to use schedule 80 pvc for the first 2 feet before and after the heater? Do I need to install a check valve?

Check valve- I only use liquid chlorine that I am adding by hand. I would think I do not need the valve unless I add a Liquidator or a in-line chlorinater.

The heater is a Raypak millivolt versa plus 151,000 btu. I was told to use schedule 80. The only reason I would not use 80 is because of the high cost. I can get the pipe and the parts.

Thanks for your help!

 

[stev32k]

I suggest you call the manufacturer and ask them. Their recommendations will be based on the heater design, heater upset conditions (loss of flow and/or plugged outlet comes to mind), and some safety factor. So I would be inclined to follow the mfg's guidelines.

 

[JasonLion]

It is fairly common to use schedule 80 CPVC for anywhere from a couple of inches to two feet after a heater because it can handle high temperatures well. Ordinary schedule 40 PVC can distort from the heat, or even occasionally melt through, if it is put right next to a heater. How crucial this is depends on which heater you have. RayPak heaters tend to only require a short CPVC adapter right next to the heater (these are usually included with the heater) and can then run regular PVC from there.

You usually only need a check valve if you have an inline tablet feeder after the heater.

 

[plucky71]

Thank you. That will help since I do have some10" stubs/sections that come straight out of the heater.

 

[amati5]

Some of online pool supplies stores suggest that CPVC is used in/out at pump, heater and filter in case of pump runs dry. Is this correct? or they just try to sell.

 

[X-PertPool]

I'm familiar with this heater. Regular PVC is fine, anything can melt. If you have the pump on a timer make sure to use a fireman switch or just make sure the heater isn't burning 30 minutes prior to shutting off the pump.

 

[plucky71]

I'm curious, what is a fireman switch.

 

[JamesW]

A Fireman’s switch is a remote On/Off switch that is connected to a heater's control panel to allow remote operation of the heater. When using a timer to control a pump, a timer that includes Fireman's switch is used to allow the timer to shut off the heater before the pump to allow the heater time to cool down before shutting off the water flow. If the water flow is shut off before the heater cools down, then residual heat inside the heater can shorten the life of the heater or possibly cause damage to the heater or nearby equipment.

The name originated from remote switches that firefighters could use in an emergency to shut off various things in an emergency. Things such as electricity, gas, appliances etc.

My preference for pump and heater connections is to use schedule 80 cpvc nipples.

http://www.usplastic.com/catalog/item.aspx?itemid=24068

 

[JasonLion]

Some of online pool supplies stores suggest that CPVC is used in/out at pump, heater and filter in case of pump runs dry. Is this correct? or they just try to sell.

At the heater it can help with heat, as discussed here. At the filter I don't see any point to using CPVC. CPVC is stronger, so it takes threading better. Most pumps take threaded pipe connections, so CPVC is often used around the pump.

 

[mas985]

I have standard PVC on the output of my heater and never had an issue. But I never expected to have an issue either because the water temp should never get hot enough to soften the PVC. PVC should not get soft until water temp gets well above 120F and most PVC pipe is speced for 140F. A 400k BTU heater should not produce more than about 16 degree rise at 40 GPM. Even a spa at 105 would not get much above 120 in the exit pipe.

 

[X-PertPool]

I have standard PVC on the output of my heater and never had an issue. But I never expected to have an issue either because the water temp should never get hot enough to soften the PVC. PVC should not get soft until water temp gets well above 120F and most PVC pipe is speced for 140F. A 400k BTU heater should not produce more than about 16 degree rise at 40 GPM. Even a spa at 105 would not get much above 120 in the exit pipe.

Well yeah, but what I was talking about was if the heater is burning and the water flow it shut off it can boil the water with the remaining heat. Also depending how the heater is plumbed you could have sufficient pressure on the pressure switch to keep the heater burning even with the pump off. I had a customer that turned some by-pass valves and ended up making the heater into a giant steam bomb. It cracked the header. So we thought the customer got lucky and ordered a new header but turns out we couldn't even attach the replacement header as the bolts that connected the header banana peeled outward from the explosion. Even if it doesn't directly melt the pvc it usually loosens up any connections and you end up having to re-plumb anyways

 

[mas985]

If there is a failure and the heater keeps running without the pump, then even the CPVC may not help. But my heater/controller, and I would assume many others, have a heater cool down mode where the controller does not allow the pump to shut off for 15 minutes while the heater cools down. Even if you don't have that, most heaters manufactures recommend that you do not shut off the pump to the heater for several minutes after the heater shuts off or you might risk damage to the heat exchanger. So for normal operation, I don't think CPVC is necessary. For extreme conditions, perhaps.

I also wanted to add that if a timer is used instead of a controller, the heater should be wired through the same switch as the pump so when the pump shuts off the heater will automatically shut off as well so you never have a situation where the heater runs without the pump running. Even if both the heater and pump shut off at the same time, I don't believe the water temperature will climb enough to soften the PVC.

 

[JasonLion]

Setups with a simple timer where the heater and pump both turn off at the same time are quite common and several heaters are specifically designed to work in that configuration.