Pool heater will not fire up.

kcopp

New install. LP gas.
2# system.
3/4" underground gas line in Constab PE. 30'
Runs to a maxitrol 325-5L.
About 20-24" of run from the maxitrol to the Pool heater.
Pool heater is just under 400k btu.
Pressure set at 14"wc static @ maxitrol
When the unit goes to fire up the pressure plummets to just under 6" w/c...
Anyt thougts?
Bad regulator?
Piping between the Maxitol and the Pool heater too short?

Thanks.

JUGHNE

How well does the 2 PSI supply hold up on the inlet side of the Maxitrol regulator when firing?

kcopp

I did not check that . There is an existing boiler and gas range on the other side that has been running fine for 6 months. That is inside on another 325 regulator.
I will check that tomorrow. Thanks.

unclejohn

Does it stay low or just a blip?

ratio

Vent limiter installed? I hate 'em. Pull it off & see what happens. The vent limiter restricts the ability of the regulator to respond quickly to pressure (flow) changes, which it must do due to the limited volume of the short nipple between the regulator & the heater. Could also be something in the pipe, even a short run like that.

& of course it could be the 2# line, as well. If that were restricted, you'd see similar issues.

EBEBRATT-Ed

What size pipe between the Maxitrol and the pool heater? I would check the Maxitrol vent connection and the inlet pressure as mentioned above. Possibly a bad regulator.

EBEBRATT-Ed

Checked the Maxitrol chart. They only talk about 0.64 specific gravity gas which is natural but reg is approved for LP as well. Don't know it this changes capacity but 325-5l there are a couple of different models-48 may be undersized-600 would do it.

Like I said couldn't find a specfic chart for LP so I could be all wrong

kcopp

There is a vent limiter on there. I was going to pull it off and stick in the standard cap.
This 325-5L is specifically for LP.
Everything is piped in 3/4"
Ideally I wanted to put the Maxitrol at the other end of the underground pipe. However @30' the 3/4" would have been undersized by 25k.

lchmb

I prefer a minimum of 5' and generally try for 10' from the unit. The vent limiter should not be installed outside anyway and when venting away I always upsize my line one size.

kcopp

Turns out to be a couple things... The 325 was not working properly and the igniter right out of the box was bad. Go figure.

Jamie Hall

Don't you love it when you have multiple failures? Makes trouble shooting so simple...

rick in Alaska

Jamie Hall said:

Don't you love it when you have multiple failures? Makes trouble shooting so simple...

I have got to the point in my career that I think all jobs have more than one problem. It just never fails
Rick

JUGHNE

And there is probably a tag/sticker indicating "This unit was test fired at the factory".

kcopp

I am thinking that the igniter issue was an install issue from the pool company.
I don't think they were exactly gentle w/ the heater...

EBEBRATT-Ed

I don't know how many times I have gone down that rabbit hole thinking , well it's new equipment thinking there is one problem and it turns out to be 2 or more.

I am better at it now in my old age, more cynical I guess I go in now and troubleshoot better instead of looking for a problem rule this out rule that out sooner or later the problem child shows it's ugly face!