indirect fired heater temperature pressure relief

Brad White_9

The typical 150 PSI/210F T&P valve is what I would use. Just make sure the BTU rating meets or exceeds the boiler rating. Commonly available item. (EDIT- Yes, ASME as Paul mentioned. I do that reflexively but forgot that many commercial valves are not so rated.Thanks Paul.)

RadPro

We are installing a Munchkin boiler to power a radiant floor heat system, along with a Superstor Ultra indirect fired water heater. We are using the 80-gal tank and the 199M boiler. For the temperature pressure relief valve on the water tank, do I need anything different than a typical hot water heater t-n-p valve?

Paul Pollets

Relief valve

The 80g tank requires the ASME relief valve (Watts #40) rather than the standard 3/4" 100XL which is used on conventional water tanks or the 60g indirect or smaller.

The instructions note this in the fine print.

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RadPro

Really? I did not see that anywere in the manual, and I tried to be thorough. Thanks for the heads up.

Unknown

wanna tell us

Thanks for the informations Paul.. Next question, what the difference between the regular relielf valve and the amse? Asides from same rating, size, paying more for amse tag?

Paul Pollets

40XL

The 40XL has higher ratings...not the same as the 100XL. It presumes the tank could have an input greater than 100K btu's.

Also the 40XL has a longer stem for insertion into a tee, unless the tank has a side tapping specifically for the relief valve.

Yes, the 40XL is pricey.

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Mike C_3

Some help?

I know in the boilers we install the manufactuer recomends a 30# blowoff and code requires a regular T&P. So we use both in conjunction on the heating side with another one on the indirect tanks. Just some food for thought.

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ScottMP

Do I read that correctly

Your code requires a T&P in the boiler ??

Scott

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Mike C_3

yup

With the GB142 it is in the state of OR considered a boiler unless it has a T&P on it then it's not. Weird I know but that's OR for you. So on the primary loop package we modify it to acomdate a 30# and a regular T&P.
So I guess it's not a code issue unless we want to spend the extra money and hassle on a boiler permit and inspection and all.
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