Heater will heat spa, but not pool?

[ntxpool]

I've never used my heater to heat the pool, but tried last weekend just to bump it a few degrees for a party. No luck.

I get the "pressure switch" error when I try to heat the pool. The heater (Laars LX400) works fine to heat the spa.....same pump, just routed to spa when in "spa mode".

Am I not getting enough flow while in pool mode....or too much flow? I tried backwashing, since the pressure was a little high on the filter, but that didn't change a thing. I know when I run in spa mode, the pressure in my system is higher (less piping), always has been, but only a tad bit higher.

Mike

 

[JasonLion]

Normally heating in pool mode "just works". However there are many many ways things might be plumbed, some of which will prevent that from working. If you post a picture of your plumbing we can probably figure it out for you.

 

[ntxpool]

Normally heating in pool mode "just works". However there are many many ways things might be plumbed, some of which will prevent that from working. If you post a picture of your plumbing we can probably figure it out for you.

Yeah, I agree....there is no reason for it NOT to work. The heater "activates", but immediately throws a "pressure switch" error, everytime when in standard "pool mode". The only thing that makes sense is the change in pressure from the spa (less plumbing = slightly higher pressure) and pool (more jets and a fountain in the spa = less pressure). But honestly, the pressure switch should have a wide range to work in. One test occurred to me: try manually turning off the spa fountain, which would give one less line for the return in "pool mode". That might up the pressure a bit.

Anyway, here's two pics.

All the plumbing (hard to see where everything goes, but I added some labels):


And a closeup of the return area that "switches" during spa/pool modes:

 

[mas985]

The pressure switch may just need to be adjusted. What is the filter pressure in pool mode? How high is the pump relative to the water level?

 

[ntxpool]

I didn't see anywhere to adjust the pressure switch in the manual, but I'll check again.

My normal pressure (per the gauge on top of the filter) is about 20-21 lbs. It was higher before I backwashed (almost 29), but didn't seem to matter.

The pump is probably 3 feet higher than the water line, but if that was a factor, I would think the heater wouldn't work in spa mode.

 

[mas985]

The only real factor is the pressure at the pressure switch. If it is not adjusted properly, the higher pressure of the spa mode might be ok but the lower pressure of the pool mode might not. But every heater should have a pressure switch and they are normally adjustable.

What is the difference in pressure between spa and pool mode?

 

[ps0303]

How long have you had the heater? There should no need to mess with the pressure switch. You could cause the unit to keep firing even if the pump is off. You should never have to mess with adjusting the switch unless the heater sits down hill from the pool/spa. Then you are adjust it to so the unit won't fire with the pressure of the water when the pump is off.

Do you run the booster pump in spa mode?

 

[mas985]

I've never used my heater to heat the pool, but tried last weekend just to bump it a few degrees for a party.

It may have never worked properly with the pool but it could also be just a bad pressure switch although usually they just stop working all together.

 

[ntxpool]

The only real factor is the pressure at the pressure switch. If it is not adjusted properly, the higher pressure of the spa mode might be ok but the lower pressure of the pool mode might not. But every heater should have a pressure switch and they are normally adjustable.

What is the difference in pressure between spa and pool mode?

Usually about 6-8 lbs. It's always been that way.

The pool and heater were installed in 2006, but I had never tried to heat the pool until last week.

The booster never runs when in spa mode......the booster is only for the Polaris pool cleaner.

I guess I'll try shutting the fountain off and see if that changes anything.

At this point, my pool has warmed up a few more degrees (it's been warm out the last few days), so from this point forward it's a battle to keep the pool cool (I live in Texas and this is a small pool....August is like bath water).