Laars Mighty Therm

Greg Swob

I have a school customer with a Laars Mighty Therm model# AP-1200-IN-09-CI-PCJX pool heater. The unit is barely 2 years old, installing firm no longer exists, so I am unsure of all past service details. It appears to have had the original ignition module changed, now has a single-wire ignition/sensor pilot assembly to a UT Electronic Controls #1003-617A module. I found an older, assumably original Honeywell module (forgot to write down model), which had two wires- one to sensor and another to spark ignitor and a pilot.

Symptom is the unit fires up on call for heat, but often snuffs out pilot, or at least pulls it away from sensor to the point of closing valve. The UT controller has one 5 minute retry and then locks out if ignition failure. The unit has a draft inducer and more than adequate combustion air. One can notice the pilot flame pull from sensor upon lightup a little. It does not shut down each time, but often enough to be a hassle for the school maintenance team. Gas pressures are at normal operating levels

One attempt to cure in the past was a shield placed at the pilot to help lessen the effect flames had on pilot. This worked for a few weeks until the shield burned out. Now, I have been called out to examine and correct problem. Naturally, when I'm there, it lights repeatedly as it should, but next day or later in day - failure.

The school is unable to get responses from Laars nor is the firm they purchased the unit from.

Has anyone experienced similar problems with one of these models? Thanks - Greg

Alan(CaliforniaRadiant)Forbes

Laars

has very good tech. support at:

(800)900-9276 x315(Jim), x398 (Arturo) 6 am-4 pm (Pacific time)

It's been awhile since I've had to call them; I hope that number is still good.

Alan

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Unknown

Greg first thing

I would do is take the thing completely apart and clean everything. I had one of these that they fooled around and fooled around and it kept doing the same thing. I got called in and we had them take it apart and clean everything, sections, burners, pilot etc.put it all back together it has been running fine for two years now.

I am suprised that Laars did not respond thye are usually pretty good. Try mhughes@laars.com or call 603-781-4815 ask for Mark Hughes.

Greg Swob

Thanks Alan & Tim

The phone #'s to Laars and Jim's extension worked perfectly. I ruled out obstruction due to dirty sections as this unit is barely two years old. Jim felt if deltaT was too great, it could lead to a premature sooting problem. Won't be able to get back in there until next tuesday. If this is the problem, it is another lesson to never rule out things by assumption. Makes sense, as it is acting just like a scorched air furnace with a partially plugged HX! Greg

Paul B._2

Pool Heater

Hi Greg,

We only install the 100% lockout ignition module on propane units and units that are ordered CSD-1. The model number you have has a J at the end and that indicates the CSD-1 requirement, so that boiler was orderd that way specifically.

The unit had the correct ignition module and pilot assembly in it. You should have found it with a Johnson controls pilot assembly on which we do not use the flame rod. The UT ignition module senses the flame signal through the ignition cable.



We have found this to be the most reliable control combination. We have not used honeywell ignition modules in quite a while on these units.

Paul B.

Paul B._2

Number is good

Hi Alan,

Arturo has Moved to a Service managers position with Jandy, and I wish him the best of luck, I'm going to miss him on the other end of the continent.

Jandy supports the Laars residential pool heaters, Basically anything 400 mbh and smaller.

The comercial pool heaters, the AP's and the CP's 500mbh and larger are supported at the number in your post.

Thanks for posting the info, and Jim and Ron are still there.

Paul B.

Paul B._2

Pool Heaters soot

up incredibly fast if the water flow goes out of whack.

If you get out there Tuesday and you can't find a manual for the unit so you can do a proper start up call me at 603-335-6300x562 and I will Fax, e-mail, carrier pidgeon, or what have you, to get you one.

Paul B.