Need smarter person than I (SPA heat)

[Channa banana]

First, let me just say a big thank you to TFP. three years countless pool companies and huge frustrations, you've finally taught me more than anyone I can hire... (and the pool is FINALLY MANAGED! if a little banged up from the fight)

But okay, help!

My spa stopped heating well last year. We have a home warranty with pool/spa included. We have had: the booster pump replaced, the filter changed from DE to cartridge, new pool pump (all things the home warranty hired pool people have said 'might be' the problem).. and a few more I'm forgetting. Now, it seems everything is fixed and filter running pretty clean, and the spa is not heating like it used to when we first moved in (3 years).

First repair guy said, "the heater is older than the both of us put together, replace it"
Warranty baulks at this sends in another pool guy who "fixes it"... thin wiring or something
The pool guys leave and I fire it up, feels slow...

Go to my old trusted TFP and do some math... from 80 degrees to 100 degrees (separate floating thermometer). 400,00BTU, average spa size, no spillover, about 70-80 ambient temp, no/little wind. Twenty minutes? An hour?

It was on for 4 hours before it reached (gasping) 100.

Called the pool people back (through warranty company)- he says, "its either on or off and its on, there's no way to test whether or not its heating fast enough. Everything's firing, thermostat is okay"... that's it. and some other stuff about propane running cooler than other gases.

Can you guys help me out? If that's with in normal parameters,
Ill leave it, but I feel I am being cheated by said home Warranty Company. And if I have to call back and tantrum I totally will, but I'm hoping you guys can help me not sound like and idiot?

Thanks in advance, you guys are lifesavers



View attachment 37579

 

[mas985]

Do you know the actual size of the spa in gallons?

But using my spa size of 700 gallons (7' spa) and a 20 degree rise requires 700 * 8.34 * 20 = 116,760 BTU. So if the heater puts out 400,000 * .80 = 320,000 BTU/h, then the time to heat is 116,760 / 320,000 = 0.365 hours ~ 22 minutes. From my experience, that is about right.

Some things to check. There is usually a screen in the gas valve where the gas pipe connects to the valve. Make sure that is clean. You can also remove all the gas injection nozzles and make sure they are clean. Normally most heaters will fault if it isn't getting enough gas but I don't know the details of your heater.

 

[Channa banana]

Ugh, I do not understand why I am having so much trouble with this, I keep getting weird numbers. Its just round, seven feet (in the picture) maybe 800 gallons?
Seven foot perfect circle (old style)

 

[OldPoolMan]

Ugh, I do not understand why I am having so much trouble with this, I keep getting weird numbers. Its just round, seven feet (in the picture) maybe 800 gallons? View attachment 37583
Seven foot perfect circle (old style)

Some questions. Does your heater run constantly on, as opposed to on and off? Ae you sure that any valves that turn the spa on are set the same way,eg Jandy Valves. If these things are correct, then you should consider where her the internal bypass is broken or destroyed, which would allow a lot of the water to nit travel thru the heat exchanger. Also, did your pool guys somehow either plumb in an outside bypass, plumb something in backwards, or something else crazy? Because its true that if the heater is firing, then the heat has to go somewhere. I think you have flow problem.

 

[bigglesworth]

Welcome Channa banana...

Beautiful pool...

To compare, my 400K BTU heater heats my 500gal spa in about 15-20 minutes (80-100 degrees). IMHO, something is wrong with the heater or the propane supply.

Just a few questions:

1) What model of heater is it?
2) What size is the propane tank?
3) What is the distance from the tank to the heater.
4) Has the regulator been checked for clogs or leaks, that sort of thing.

 

[Channa banana]

I do apologize and thank you. I hadn't saved my signature correctly before the original post.

Gallons of propane, 250 (80%)
Distance from Tank, 7-9 feet
Pentair OS
The regulator? good question- This may fall in the gray area between pool (under warranty) and propane (Their job to make sure its up and running correctly) I'll certainly check it or have hubby check.

Todays adventures?
Are the filters too dirty? NOPE
Is it firing ON- YEP
All burners- YEP

I left twice and came back to find only the pilot still burning (like a auto off situation, but no call for it to be off because the Pentair, still reads 80/100, calling for heat)

My suspicion? - now we all know it takes four hours to heat 700gallons twenty degrees, with only a pilot and an intermintent (if that) heater.

I can get the Home people to send someone out again- but I have a feeling that if I don't know whats wrong…I wont be able to tell them what to do

Help?

 

[mas985]

Does the heater have any sort of LED readout to show error codes? It sounds like either the pressure switch or thermal limiter switch is shutting the unit off but you should get some sort of error code. Might also be the temperature gauge or is the heater controlled by external controller?

 

[bigglesworth]

My first step would be to troubleshoot the fuel supply. I'm not sure if the warranty company will do this or not, but have someone come over with a manometer and check pressure at the heater. The pressure should be about 10-11 WC... I believe this is correct; Please anyone with propane heater experience, correct me. Obviously there's enough pressure to keep the pilot on, but maybe not enough to actually heat.

If you have adequate pressure, then you need to look at the heater. Maybe the some of the gas nozzles are plugged or maybe something with the heat exchanger/tube coil (soot, corrosion, blockage???). Did you actually pull the burners out to look at them. Maybe there's blockage of some sort inside or outside?

Just to make sure; Is the heater actually running the entire time during the 4 hours or is it cycling (turning off, turning on, turning off, turning back on again...). Obviously it's supposed to run the entire time until the water is heated to the correct temp... but just checking.

 

[Channa banana]

The heater is extremely old (I'm pretty sure that Barney Rubble lights it on the inside) that's why the first pool guy wouldn't touch it. Just on/off switch and a low/high dial.

The heater burns well, all burners clean/hot, pilot stays on... It seems more like its cycling on and off.

The pool guys said he replaced a thermostat wire... (but its bigger and better)

But the pentair is still reading a normal temp.

I can not stand a mystery~most go wrench some more

 

[Channa banana]

So it seems like it shuts off as soon as it makes a degree of progress. I can shut it off, wait awhile, and then turn it back on where it'll start up fine blazing, (five minutes) -shut down, pilot on. It won't restart right away (if I trip the breaker, reset, ECT.) only after ten? or so minutes, like a cool down? IDK?

So if I-

Turn on - therm reads 65/90
heater blazes
therm hits 66
shut down
(try restarts of many forms and running under service or time out) - no heat
Wait ten minutes and repeat process
Therm reads 66/90
Heater turns on
67
shut down

I could probably get it all the way hot this way but

Can someone give me a name? Is it the high temp shut off switch? anything I can swing at the Warranty company? Makes me want to be a less honest person...I could have destroyed it by now just and had them fix it

I really appreciate anyone pointing me the right way

 

[OldPoolMan]

Hi Channa. As I mentioned in my earlier post, your heater is obviously cycling on and off. So, unless its a gas pressure issue, it's a flow issue. That means, 1. Bad pressure switch. 2. Plugged filter. 3. The heat exchanger is lined up and causing the heater to cycle on and off via the high limit switch. 4. The bypass is stuck or destroyed, which either way causes cycling on and of. Item 4 is likely. The old Laars heaters have a bypass made up of a spring and 4" plastic disk. Easy to acess, its next to the heater inlet and outlet pipes