Heaters and flow

[rjb1211]

Once you are over the minimum flow required for a heater does the amount of flow have any impact on the heaters performance?

I understand BTUs and how to calculate heat rise for a given pool volume, but was wondering if the amount of water passing through the heater had any impact. I just installed a VS pump and was thinking about what the sweet spot would be to run it (if there is one) when the heater is on. If it makes a difference the heater is a Mastertemp 400 LP.

 

[mknauss]

Once you meet the minimum flow rate to operate the heater, there is little reason to run at a higher flow rate. The heat transfer is the same, and thus rate of temperature rise in the pool is the same.

 

[rjb1211]

I looked up the minimum flow for my heater and found this:

Would that maximum flow be for heater efficiency or so the internals are not damaged?

 

[ajw22]

Would that maximum flow be for heater efficiency or so the internals are not damaged?

Maximum flow is to prevent erosion of the copper heat exchanger.

 

[swamprat69]

A higher flow rate would definitely increase the heat transfer coefficient, but the increase would not be proportional. The increase in the heat transfer coefficient would be minimal ( mid to low single digit percentage rise at most) and would entail a higher cost for running the pump at a higher speed. In other words even doubling the flow rate would not double the heat transfer coefficient. Water flow rate will effect wear on the heat exchanger at higher rates.

 

[rjb1211]

Maximum flow is to prevent erosion of the copper heat exchanger.

How much cushion is in that number? Would it be wise to limit the flow to a smaller number?

 

[ajw22]

How much cushion is in that number? Would it be wise to limit the flow to a smaller number?

You cannot push close to 120GPM through your equipment so why are you worried about it?

 

[rjb1211]

You cannot push close to 120GPM through your equipment so why are you worried about it?

I thought I could get close to that. After checking I see I max out at around 100. Thanks.

Edit: I see I needed to change my signature to represent the new equipment.