mastertemp 300hd Cyclinginginginginging

[Glen Innes]

Hi all, I'm a long time fan , first time seeker of help on tfp. I have an in ground pool/spa with a pentair mastertemp 300hd heater installed 2013. Pool has inbuilt cleaning and is intelliflow controlled. Serviced regularly, pool is salt with good water Chem. Varriable Pump at 2300rpm. So all's well until a few weeks ago when the heater starts cycling. First it was a few min"s then sec's then ten min, then sec's again no real pattern Pentair service guy comes out spends 8hrs over 2 days testing and lamenting and finally gives an invoice with the conclusion "touch pad replaced X$$, how ever " heater beyond economical repair". Wow. He states that he can t find anything wrong with it and it might be sooted up. So i decide to open the can. No soot. no water gave it a vac and the pipes a clean with and put it back together. Still cycles no change.
So heres the some data - Call for heat- Fan on ( never stops in mode) - click - gas - ignition runs??? flame out - call for heat .........
Gas type lpg. no error codes ever / no service leds ever / no ICM leds ever / no lockout ever
nano readings 3.1 static -2.8 dynamic - new igniter ohms 75
Water flow ok, - Filters Clean - Pressure switch ok / jumped and multi -Thermal reg opens no prob - new thermaster ok /jumped and multi
new fenwal plus added extra ground wire / multi tested ok - new PCB - HLS and AGS ok /jumped and multi - SFS jumped and multi.
All this and the unit is in good order with no corrosion or damage. So what have i or pentair guy overlooked? It does heat to the set temp eventually, but just cycles its way there and sometimes even goes for 30mins without cycling. Sometimes it just doesnt want to play and endlessly cycles in 45sec - 1min intervals for as long as i let it without stopping and never gets to temp.
hoping the gurus of tfp can help.
TXGi

 

[JamesW]

nano readings 3.1 static -2.8 dynamic

What does this mean?

What is the flame current?

What is the gas pressure?

Do you have a video of the heater running?

Is the water temperature reading correct?

Do you have a picture of the system?

 

[Glen Innes]

Hi James thanks heaps for responding, the nanometer reading is what the service guy took from the gas unit in the heater, 3.1 whilst the unit was not lit and 2.8 whilst it was going. (usually 1-2min at times) He had a funny set up of small hoses and he mucked around there and adjusted something, she sounds fine when actually heating. He checked the the pressure, water trap and gas regulator at the inlet and said it was well within range. i dont know the numbers of that. The water temp as it reads on the heater is about (24*C) 1*C less than the intellifow 23*C and about the same 2*C+/- as a manual reading from the pool with the floating thermometer. The temp reading doesn't jump around and the flue temp gets to about 260*C+ if running for a bit. Sorry i'm unsure what "flame current" reading is. But he put a multimeter on everything including the 2 little pins on the fenwal unit and said it was reading correctly for ignition and subsequent flame No (flame current reading maybe) he said that it needed to be greater than 0.00?1 and less than 240v in . He was dumb struck that all switches when tripped displayed as a led code on the pcb but nothing as it cycled on/off and kept at the fenwal or gas as the issue but could find nothing out of the norm. i will take photos and/or a video tonight so you can have a gander at the setup.
tx Gi

 

[JamesW]

nanometer reading is what the service guy took from the gas unit in the heater, 3.1 whilst the unit was not lit and 2.8 whilst it was going.

The heater requires a gas supply of not less than 4" (10.2 cm) wc and not more than 14" (35.6 cm) wc.

Gas supply pressures outside of this range may result in improper burner operation.

A minimum flowing or dynamic inlet pressure (while the heater is running) of 4" (10.2cm) wc is required to maintain input rating with no more than a 2” pressure drop between static and dynamic.

Based on the manometer readings, the gas pressure is insufficient.

 

[swamprat69]

This may or may not be relevant, but I have seen a similar problem with a gas furnace that would fire up but drop out within a couple minutes. The gas pressure would drop to a point that was insufficient to support a flame at the burners. After checking back to both the gas meter outlet and inlet, I found that the gas pressure was also dropping upstream of both the meter inlet and regulator. Gas Supplier finally traced it to a corroded/breached line to the meter that only maintained some partial pressure due to being buried.

 

[Glen Innes]

Some photos

 

[Glen Innes]

Wow thanks James that’s so obvious I ve even read that in the manual I think. I know the pentair guy is a plumber who got the job because we live a bit outback , but that’s no reason to miss that. He charges like a wounded bull as well so we got no change out of 850$. Yep he’s got all the gear but is a useless as **** on bull. I’m so happy I’ve got something to go on I’ll be darkening his door step In the morning to get him back to up the gas. For my info what does he need to do in case he gives me a song and dance routine about the whole thiing
Thanks heaps James and swamp rat for helping out. I will post the outcome or pentair guys obituary which ever get a result
Tagigan

 

[JamesW]

I would check the regulators to see if they are correct since the problem happens before the heater is running.

How far away is the propane tank?

 

[Glen Innes]

G'Morning James, The tank is a 2500 litre tank about 20 metres away, and the regulator is in one of the pics, nothing has changed on the setup since 2013 so i guess time has wearied it. I somewhat expected the response from pentair/plumber guy i got this morning as he said he was "wearing his pentair service hat" on whilst looking at the heater not his "Plumber Hat" and can organize a gas fitter to come and look at the setup in few weeks , after which if required he can come and tweek the heater for a flat rate. So a ute full of hats i thought! Well, now at work and took off my "Putz hat" and put on my '"Don't get mad get even Hat" . i figure i can arrange my own gas fitter and wash my hands of the Hat man. Your insight and advice has been so refreshing James thanks mate.
Txgi

 

[Glen Innes]

"Thinking Hat" on now , - if the pentair guy said he adjusted the gas he must have played with (2nd stage regulator) ,the inlet regulator yes? i read in the manual and it seems to imply that everything is factory set in the manifold/regulator (no adjustment?) and as you pointed out James it requires 4"water column of pressure min. So a licence gas fitter , introduced to the manual of course should be able to get the right regulator adjustment, hopefully? maybe? with the right hat on? i live about 120km from the nearest town so its a lottery of the available, the skilled, and the willing to travel here and throwing money at them dosen,t always cut it.
Txgi

 

[JamesW]

There should be a valve and a regulator at the tank and a valve and a regulator near the heater.

Hopefully, a gas contractor will be able to figure out why the gas pressure is too low.

 

[Glen Innes]

Thankyou James, I will endeavour to post the outcome when I have this checked. Once again your selfless time to help has won the day and I am very gratefully thanks mate.
Glen

 

[Glen Innes]

Back again and still no wiser. So gas fitter came today and checked the regulators, propane tank and 1 stage regulator all good. 2nd stage regulator for the heater ( exclusively) was all good too . He set up his nanometer to test inlet pressure on the heater as set out in the manual and it was within the limit 3.40kpa static and 2.90 dynamic the manual say min2.75 as min. He upped the Kpa to 3.40 dynamic but no change, then set it back to the required. And on with the cycling , only now it only stays on for 10 or 20 sec over and over, no service leds, no error code. His job done I shouted him a beer as we sat and listened to the endless on off on off over and over the endless rhythm of 300hd. Anything I haven’t tried ?? Or should have. Anything at wits end
Tx gi

 

[JamesW]

Check the flame current.

Heater Flame Sensing - Further Reading

www.troublefreepool.com

Note that when you are posting measurements, you should always include the units every time.

Never assume that the other person is using the same units that you are.

Gas pressure can be reported in several different units. In your earlier posts, you are not clear about the units, which probably caused you to do unnecessary work.

Always over index on clarity.

 

[swamprat69]

You need to isolate exactly what is causing the heater to drop out. For example starting with do you lose 24 volts at the gas valve when the heater drops out? If yes, do you lose 24 volts between "TH" and "GND" at the fenwal ignition module when the heater drops out? If yes, which safety is opening to cause the loss of 24 volts between "TH" and "GND" at the fenwal. If no, it would seem to point to either a flame signal problem or a problem with the fenwal ignition control itself. You are essentially tracing backward from the endpoint of the circuit to determine where you are losing the circuit voltage. Loss of gas pressure is only one of several reasons for dropout with a constant 24 volts to "TH" and "GND" at the fenwal. Electrical and connection diagrams can be found here MasterTemp Heater Installtion and User's Guide (04/07/06) (inyopools.com)

 

[Glen Innes]

Thanks guys, your point on different index units is something Johno (the gas guy ) picked up on. I was showing him he manual the former tech down loaded and he noted that the values where all imperial ie. Wc and inches and no AS/NZS gas accreditations. He said we measure everything in Kpa . and the unit would be set up for sale in Aus with a AS/NZS cert. His nonometer could convert to wc (inh2o). So back to the interweb and yep there's a manual for Aus which differs on fewpoints from the USA one. So here,s a pic of the gas

 

[JamesW]

Check the flame current.

 

[Glen Innes]

I had read the "Further reading" flame sensing article some weeks back its a great step by step explanation with tips. I have already installed a new IcM, ignitor and a pcb etc etc. and getting a reading of about 1- 2 vdc on the fc+/- pins. I ve also tried plugging the unit into a different circuit. i cant find any leakage but with so a minute ampage required i could be wrong. I will digest your testing ideas Swamprat because i think the gas valve is a slightly different setup but the schematic seems the same. I thought i might set up a few grn points on the unit as well ie. 5/6 from multiple contact points on the can. More the merrier maybe? all ideas welcome at this point. thanks James and Swamprat for your feed back.
tx gi

 

[Glen Innes]

thanks James , just to be sure to be sure the measure rectification current ? ( flame current or flame on) at the fenwall points Fc+/-
or is there a another way?
txgi

 

[Glen Innes]

So did some of the things you suggested swamp rat and yes had 24vac to the gas modual that stoped when heat drop out . Had 24vac at th/grn and Val/grn which didn’t drop out. And found in the manual a note about not adjusting the gas at the regulator.?? See my attachments very confused about the 11pa +-5pa at the vent tap manifold??? Also the burner trouble shooting no2 burner not stay lit. To lean? How do you adjust it. Checked the gas orafice to be sure and the seal is good an 6.6mm so with the piping set as per manual how do I read and adjust the vent tap to 11pa I know the manometer will read differential so why let us know about it in the manual without explaining i? The biggy today was not getting a vdc reading from the fc pins like before I only got a vac read that dropped out with the flame so I think sensing is an issue even with the aux grn from the flame holder. Beeroclock now tx gi
so what’s this thing*9