Added Heater- PSI increases

[generessler]

I inherited a Mastertemp 400 with the pool when we bought our house about a year and a half ago. Sellers said the heater was two years old.

I have a similar situation. With the bypass valve set to bypass, pressure is about 12lb with clean filter and jumps to 18 with the bypass sending water through the heater. Also the sound of the flow is a bit rougher with the heater switched.

 

[pjt]

Did you also have a bypass installed? Using a bypass will increase the efficiency of your system when you're not heating the water.

 

[generessler]

Did you also have a bypass installed? Using a bypass will increase the efficiency of your system when you're not heating the water.

Thanks. Yeah that's the whole point. There is a bypass valve. With the bypass off, all flow goes through the heater. The system pressure is 6-8 psi higher than when I turn it on (all flow goes direct to returns).

So it's 13 psi vs 20. I'm asking if that's normal. Seems too high.

We use the heater only for the spa. It would be nice not to have to dink with the bypass valve - which is not easy to get at - every time we want to turn the heater on.... Or risk forgetting and hope the flow switch prevents a meltdown.

 

[HermanTX]

Yes - flow through the heater will always cause more backpressure to the system because of the diameter and number of coils in the heater. Also, if you are in spa mode, the jets tend to be a smaller diameter in a spa which also causes back pressure to the system compared to when in Pool mode and straight to the returns.

 

[mknauss]

Very little of the water goes through the heat exchanger when the heater is not operating. There is an internal bypass in the heater. It does create some backpressure. A VS pump will help relieve that tremendously for you. It will be your next pump when the current one fails.