Plumbing Question For AG Pool

tnt69

Member
May 27, 2016
11
Chester, IL
I have purchased a new pump (Waterway PH2200-6 2hp 2speed) and a new gas heater (Hayward H400FDN) for our 21 X 43 ft oval pool. I have my Brother in law (certified heating and cooling & electrician) hooking up the heater and I see in the installation notes to install a flow meter on the outlet line of the heater. The min/max flow rate for this heater is 30 and 125 GPM. I have 1.5 inch plumbing on the original pump and heater and planned the same for this too. First of all, I have 4 90 degree elbows between the filter and heater intake. Would I be better off to use 2 inch pvc for this section even though the filter output is 1.5 inch? And secondly, this flow meter on the outlet side of the heater, I cannot find a flow meter with even close to the range I need (30 & 125 gpm) in a 1.5 inch size and 2 inch flow meters are much closer but still fall short. Is this flow meter really necessary?
 

cfherrman

TFP Guide
May 10, 2017
2,410
Hays, Kansas
What was old hp of the pump, I'm not looking at charts or running numbers but 2" sounds more correct for a 2 hp on high especially with 4 90's (equals 20-25' of pipe). The 1.5" connections don't really mean that much, just adds a few feet such as a 90 does.

Irc you just need to make the flow switch happy on the heater, so if low closes the switch then the heater should be fine, might want to search on heater flow switches though.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
11,678
Northern NJ
A flow meter is nice to have but most of us don't have one. You know you have adequate flow if you satisfy the pressure switch on the heater and it turns on. Too high flow can wear out the heat exchanger prematurely.

Look at the Flovis if you want to put in a flow meter - FlowVis — H2flow Controls But it is not necessary.

What is more important is plumbing a heater bypass using a 3 way Jandy valve and a check valve. That let's you bypass the heater fully if your pool water is questionsble and may damage the heater. You can also crack the bypass valve open a bit if your flow is too high and let some water bypass the heater.
 

tnt69

Member
May 27, 2016
11
Chester, IL
The old pump was basically the same, a Waterway 2hp 2 speed pump. My thinking was the same about all the 90 degree elbows so I was planning on using 2 inch pvc from my 1st Pentair 3 way valve (which I guess is basically a Jandy valve?) through the 90 degree elbows into and out of the heater and back to the 2nd Pentair 3 way valve where I will go back to 1.5 inch to the pool return. I have 1.5 inch coming out of the filter to the 2 Pentair 3 way valves running a straight shot to the return as a bypass for when the heater is not being used, which is probably 90+% of the time. I can set these Pentair valves to allow a small % of the flow to bypass the heater when I am heating the pool. I just wish there was a flow meter that was cost effective considering after the system is all up and running, the flow meter is not that important once I know what my Low and High already is. Thanks for your input, it does confirm my thoughts. Would it be possible to use Flex connectors on this project to make it easy to take apart for winterizing?
 
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