Bought a new heater - now I need a new filter?

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R

rjmac

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LifeTime Supporter
Sep 7, 2010
26
El Paso, TX
Our old 250k BTU heater died, so we bought a new Raypak Lo-NOx 400k BTU gas heater (less than $2k online). We upsized because from what I had read, bigger is better with respect to pool heaters. We maintain the pool ourselves - hubby handles maintenance, I handle the chemistry. So far we've made a pretty good team, but installing the heater was a little beyond our skill level. So we called the pool guy (relative of a relative) for installation, and he says that while we got a great pool heater, our filter isn't big enough to support it. We have a Hayward Star-Clear Plus cartridge filter - 90sf. He says we need to upgrade to a DE or sand filter - 48 sf. Does this sound right? He says that the heater won't get enough water pressure with our existing filter so it won't fire up right. I don't think he's trying to pool-store us, but I just wanted to get another opinion. Thoughts?

If we do upgrade our filter, we'll be getting a DE over a sand filter. Luckily, we used to have a sand filter, so the back wash system is in place. Any recommendations on DE filters? I'm just beginning this new line of research, so any direction would be much appreciated. He recommended the Pentair FNS. Thoughts?

Thanks in advance!
Jill
 
Your heater requires a minimum flow rate of 40 GPM. The Star Clear Plus C900 is rated up to 90 GPM for residential applications. Therefore, the filter should be able to handle the minimum required flow rate of the heater.

Sometimes, it can be tricky to get a heater to operate near the lower end of the flow rate because it contains a pressure switch and not a flow switch.

The pressure switch is factory set at 1.75 psi. This means that the pressure after the heater has to be at least 1.75 psi. This also assumes that the heater is at standard deck level. If the heater is not installed at deck level, then the pressure switch needs to be adjusted, or replaced by a flow switch.

The pressure switch can be adjusted, the back-pressure can be adjusted, or a flow switch can be installed in place of the pressure switch. I would target a flow rate of about 45 gpm. It is important to get the installation right or the heater can be ruined. I would use a flowmeter to verify that the heater is receiving the correct flow rate.

Sometimes adding directional eyeballs is enough to create the required backpressure to close the water pressure switch.

What pump do you have?

What is the normal filter pressure?

Also, did you verify that the gas supply would be adequate for the new larger heater?
 
Thanks, James.

The pump is a Hayward 1.5 hp pump. The normal filter pressure is between 16 and 20 psi. I was wrong about the filter - it's a C1200 - so 120 sf, and it's rated at 45 gpm. Yes - the gas supply is adequate. We had a new larger meter installed about 35 feet away from the heater (direct, no turns) with a brand new 2" line. We were very fortunate that the gas company installed all new meters and lines in our neighborhood a few months ago.

The pool guy is saying the minimum cartridge filter size that our new Raypak heater requires is 200 sf. ???
 
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Ill just leave this here

* edit after reading the entire manual, No Where is there a specific requirement for filtering area...
 
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