Jandy ain't dandy...

[alacrity]

This thing has been driving me crazy. It's fine... then I go away and my wife tries to heat the spa and.. it's not fine. I am starting to think it's personal. Like CHRISTINE the killer car.
argh.
So we have a properly functioning pool system (it seems) in all other ways. Diatomacious earth filter gets semi-annual re-do... and shows 10-20 psi after a top bleed consistently. Pumps work perfectly, automation switches are good and the servos to change pool-spa-pool are good.
The heater shows LOW PRESSURE sometimes and there doesn't seem to be rhyme nor reason to it.
It's also home to a bunch of nasty black widow spiders, so I wouldn't mind if the thing just exploded in general.
But... I should probably just fix it. I've no training in this or hvac etc, but I restore and build custom/vintage motorcycles so I know how to spin a wrench. My gut says it's a wonky pressure switch (where would that be located?) and... anyone have a quick and dirty way to use an ohmmeter to find out if this one is copacetic or not?

 

[alacrity]

i was gonna add more pix but the system won't let me -- ?

 

[Richard320]

Look for something screwed into the plumbing with a grey and a purple wire connecting to it. Well... if this is the manual for your heater: http://www.zodiacpoolsystems.com//~/media/zodiac/global/downloads/h/h0286900

If you jumper it and the thing works, either the switch is bad or you have low pressure. The 15 psi you have ought to be enough to close the thing. Page 36 of that manual shows what the switch looks like and how to adjust it. Page 53 is an exploded view of things.

 

[PAGirl]

i was gonna add more pix but the system won't let me -- ?

Upload to a service such as Photobucket, then paste the IMG link into the post.

 

[alacrity]

Upload to a service such as Photobucket, then paste the IMG link into the post.

Ok i will, thanks!!

 

[alacrity]

Look for something screwed into the plumbing with a grey and a purple wire connecting to it. Well... if this is the manual for your heater: http://www.zodiacpoolsystems.com//~/media/zodiac/global/downloads/h/h0286900

If you jumper it and the thing works, either the switch is bad or you have low pressure. The 15 psi you have ought to be enough to close the thing. Page 36 of that manual shows what the switch looks like and how to adjust it. Page 53 is an exploded view of things.

thanks Richard! I have the older version - the LX, but it seems most if not all of it is the same. I hope the pressure switch hasn't migrated... Gonna pull it apart tomorrow (before watching MotoGP from Indianapolis!!)

 

[alacrity]

more pics of my overall setup. sorry for the blurriness -- the spiders made me jumpy.

 

[ps0303]

If you are doing regular maintenance on the filter and keeping it clean, it's probably the pressure switch. Like Richard320 said, you can jump it out and if the heater works, then it's the switch or water flow. Once you verify water isn't the issue, then the switch becomes the suspect.

 

[alacrity]

If you are doing regular maintenance on the filter and keeping it clean, it's probably the pressure switch. Like Richard320 said, you can jump it out and if the heater works, then it's the switch or water flow. Once you verify water isn't the issue, then the switch becomes the suspect.

Got it - but how would one know if in fact it's the water flow itself? I mean - is there a separate way to test that? It only takes a couple psi to shove the plunger in the switch so it makes contact and opens the circuit, right? So am i right in that pretty much any positive flow should kick it open? I can see LOTS of pressure flowing into the pool-- the pool sweeper flies around like it always has when all pressure is directed that way, and on spa setting, there is a lot of active circulation and flow. There is also none of the telltale air-gapping (sounds of whack/bang) from the heater core or piping that one gets if water flow is low and the pump is sucking/pumping air. What gauge wire do you recommend for the jump? I don't know how many amps are travelling along that line...

 

[alacrity]

this seems like the right schematic... yes? Jandy Laars LX/LT Heater Parts

 

[ps0303]

Nothing special on the gauge of wire for jumping out the switch.

I usually test the pressure by placing my hand on one of the pool inlets and if it's strong enough to push my hand away, enough pressure is there. If I can hold my hand over the inlet with little effort, probably not enough water pressure.

 

[Richard320]

My reading of the adjustment procedure on that switch was that it looks for some kind of differential pressure - about 2 psi.

The pressure switch is preset at the factory for activation
at 2 psi (14 kPa). Do not adjust the pressure switch if
the heater is installed more than 15 feet (4.57 m) below
the pool surface. Consult your local Jandy Pro Series
representative for recommendations.
BYPASS
ADJUSTMENT
SCREW
THERMOMETER WITH
PETE’S PLUG®
Figure 34. Temperature Rise Measurement
On some installations, the piping from the heater to the
pool is very short. The back pressure could be too low
to trigger the pressure switch. If this happens, it may be
necessary to install a directional fitting or elbows where
the return line enters the pool. This will increase back
pressure enough for the heater to operate properly.

 

[alacrity]

Nothing special on the gauge of wire for jumping out the switch.

I usually test the pressure by placing my hand on one of the pool inlets and if it's strong enough to push my hand away, enough pressure is there. If I can hold my hand over the inlet with little effort, probably not enough water pressure.

There is PLENTY of pressure by this test. thanks.

- - - Updated - - -

Richard: I saw that in the service manual you posted...

I also found what appears to be the right manual for this particular (older) LX heater here

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCIQFjAAahUKEwiw1IyZ1pzHAhURW4gKHWLqB2s&url=http%3A%2F%2Fedc.poolsupplyworld.com%2Fwpdf%2Fjandylxltpoolheater-manual.pdf&ei=s6HHVfCuNpG2oQTi1J_YBg&usg=AFQjCNG-6cowOdisKy7ycDEsVFyR7AuLhw&bvm=bv.99804247,d.cGU


What I would love to find (but haven't yet) is a couple pix or a video showing the easy way to remove the panels to get to the pressure switch. I have the lower front cover off -as you see in the pix. Given the spiders etc (I know I sound like a weenie - but these black widows are not to be trifled with)... I don't wanna be reaching up inside under the top front cover. Does the whole top come off?

 

[Richard320]

Haven't got a clue.

 

[jblizzle]

What do you mean the filter pressure is 10-20psi? That is a huge range. We recommend backwashing when the pressure rises 20-25% or the flow drops too much. If you have a clean pressure of 10 psi, then there will be virtually no flow by 20psi.

 

[Qwaxalot]

this seems like the right schematic... yes? Jandy Laars LX/LT Heater Parts

Pressure switch is behind the upper front panel (#59 in the parts breakdown). It's secured by screws running vertically from the bottom of the panel. Remove the screws and the panel slides down.

 

[Qwaxalot]

One more comment. This unit displays the pressure switch error when (in remote operation) there is no call for heat. That is, the Aqualink thinks it's set temperature has been reached (a more complete explanation is in the Jandy manual).

 

[Ale_Brewer]

Just to cover the obvious things...Are you sure the "low pressure" is in reference to the water and not the gas?

 

[ps0303]

Pool heaters have no way of knowing about gas or pressure.

 

[Ale_Brewer]

You see in the pic the sticker that says '3.0" WC'? That refers to the minimum gas pressure required going into the unit while the inlet valve is open. That refers to 3 inches of water column which is a measurement of pressure. Three inches of water column is equivalent to 0.108 PSI. The regulator coming off the gas meter that supplies your house should be a 0.25 PSI regulator which is the standard for all residential appliances that use natural gas. This being said, you should have 0.25psi before inlet valve with valve closed. When valve opens, you should have at absolute minimum 0.108psi. Anything less than that, your heater will shut down due to low gas pressure. Just a note about something related, if your flame is burning on low pressure, it will create more soot than usual which will build up on your flame sensor causing it to fail prematurely.