How long should I wait for an emptied steam boiler to cool before adding new cold water

sreja

A Large steam boiler (40-60 gallon capacity) was hot and generating steam.
It was turned off and drained completely.

Now the question: How long should I safely wait for it to cool before I can refill it with cold water?

BobC

The water coming in is at about 50 degrees, you don't wand to flood that into a hot boiler. Wait until it's just very warm, not hot, and then fill it slowly so the iron does not get shocked.

Bob

sreja

That's my problem -- I don't have a good idea of how long it will take such a large piece of metal to go from hot to warm and it's all insulated so not so easy to just reach out and touch to feel. That's why I'm looking for some kind of estimate of how long I should wait..

nicholas bonham-carter

Hello again! Does that mean you have just replaced the underfloor, leaking return?
Feel the pigtail, or the Pressure relief valve, and when they can be touched, and held, then it should be safe to fill it up slowly.--NBC

Fred

My pigtail and pressure relief valve cool way faster than the boiler. They are exposed to the air and much less mass. I would wait at least 5 or 6 hours to be safe.

sreja

Thanks all for the advice. I waited a few hours and until everything i could lay my hands on was luke warm.

hi nbc!! long time no see. I can't say i love the new format of the forum here, but as long as you and the others and the old content is still here, i'm happy!

no we didn't dig up the mystery leaking return, just living with it as best we can.

j a_2

As long as the fill is piped correctly, and its not making steam…a slow fill in my opinion is ok…As some people call them, automatic water feeders, i call them low water backups….They fill on demand and they don’t care what the temp of the boiler is..Me I don’t like them…A boiler and especially steam boilers need looking at….

Dave0176

j a said:

As long as the fill is piped correctly, and its not making steam…a slow fill in my opinion is ok…As some people call them, automatic water feeders, i call them low water backups….They fill on demand and they don’t care what the temp of the boiler is..Me I don’t like them…A boiler and especially steam boilers need looking at….

I agree, I've very slowly filled a hot boiler with cold water, it's PITA, but it'll have to do until you pipe it into your water heater.

I don't care for water feeders either, I've only installed two, one a customer requested it, the other was an apartment building.