adjust gas valve w/o combustion analyzer?

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I have a Munchkin T80M. I like to experiment, and I wanted to see if I could squeeze a little extra efficiency by adjusting the throttle (which changes the gas flow rate and thus the gas/air ratio).

Now I know I'm not supposed to do this without checking the result with a combustion analyzer. I don't have such a thing, though, and it is too expensive for amateurs.

My idea was to adjust the throttle just a little at a time, only reducing the gas flow rate, never increasing it. My question is, what could happen if I go too far? Presumably the flame may go out or become flaky and unreliable, but the boiler isn't going to self-destruct or explode or anything, right?

Should I turn the throttle a 1/4 turn at a time or a whole turn or more at a time?

If I reduce the gas flow, does that derate the boiler so it won't be able to put out 80,000 BTU/hr any more? (I don't want to do that; I just want to find the ideal balance.)

If my plan is a bad one, where can I get a homeowner-grade combustion analyzer?

Many thanks for your help and advice!!

steve gates

with my limited experience on muchkins I'd say can't be done. If the trottle your speaking of is the little scew on top of the gas valve it can be very sensitive. A little off and you'll get flutter and shut down.

Without an anyliser how will you know?

jalcoplumb_2

If you have...

adjusted the screw w/o an analyzer, Call A Professional Immediately!!! You could create deposits on the heat exchanger and flame rod that will drop your performance and shutdown the boiler. You could void your warranty.

There is no homeowner-grade analyzer. You need training to know what you are doing. I think between the analyzer and the training you could call a professional and it would cost you less.

The Munchkin has parameters listed in the install manual. These should be adhered to.

A Pro will adjust the combustion and print out the results for you.

Joseph A Landree
JAL Co.
Allentown, NJ

Mark Hunt

DANGER!


Your CO numbers can go thorugh the roof and the unit will eventually fail to operate.

This is not an area that you should be "experimenting" in.

If you made any adjustments to that boiler, you need to get a qualified technician back in there to undo what you did.

Was the boiler ever set up with an analyser?

Mark H

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> Was the

> boiler ever set up with an analyser?


No, not as far as I know. There's no hole in the PVC...would they have needed to make a hole to do the adjustmnt during installation?

And no, I have not done anything with the throttle yet. I thought I'd check first.

But why should my CO numbers go throuh the roof if I am reducing the gas, not increasing it? (I know which way to turn the screw to do that.) And why should there be deposits, as another post says? I'm not arguing, just trying to learn.

Mark Hunt

Here's why


You can get high CO on either side of the fuel mixture.

Also, if that boiler was not set up with a combustion analyser it was not done correctly.

You should call HTP on Monday to see if they know of a contractor in your area familiar with the Munchkin.

Mark H

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If the PVC exhaust piping does not have a (sealed) hole in it, is this clear evidence that a combustion analysis was NOT done during installation? Or is there another way to access the exhaust gases?

Many thanks,

Mark Hunt

I suppose


they could have done it outside at the termination, but the results would have been questionable.

They would have had to go out side, take a reading, then come back inside and make the adjustment, then back outside for another reading, etc......................................

Highly unlikely.

How long has the unit been in operation?

Mark H

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> How long has the unit been in operation?


New this season (installed 9/04).

Last question (I hope): how is it done when the boiler in question requires stainless-steel venting? Does one still make a hole in the stainless?

Mark Hunt

Yes


We use high temp silicone to seal the hole on SS pipe.

For PVC vented units, we have a drill bit that makes a hole and then taps it for a 1/4" brass plug.

HTP specifically requires a combustion test be performed on all of their boilers. It is the only way to ensure proper operation.

If something goes wrong and your boiler fails to operate, who will service it? If the company that installed it does not know how to do a proper set up, how will they know how to fix the boiler?

If they call the factory for support, the first question they will be asked is "what are your combustion numbers?".

I am an advocate of testing EVERY combustion appliance, but the Munchkin absolutely has to be set up this way.

I would call HTP on Monday to see if there are any factory authorized people in your area.

Mark H

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Wes Weber

adjusting

A friend once told me and I Qoute "They made a decision at the factory" This is for a reason. as a home owner you should not touch that boiler. And what ever happens if you do be honest and tell the pro when he comes (and he will have to come) everything you did. This will make your bill less and his job less trouble. You will probably most assuredly void any warranty.

Do what you do best.

Thomas Mörtberg

Adjustments should only be done with an analyzer. Personally I dont think there will be an efficiency gain due to the increased excess air. As for testing from the outside termination, I have checked combustion from the termination.