what cause sa hot water boiler to flash to steam...limit @ 190

oil-2-4-6-gas

i just came from the same exact call ---basement renovated turned into an apartment --the zone was airbound --cold water in the pipes then the pump would move a little water ---hit cold water say at 65* with a little 190* makes a lot of noise -purged the system --end of problem --

bluemoon

I have a hot water boiler...limit set @ 190 & satisfied...a new zone comes on line & the return hammers like crazy...steam?

Big Ed

New Zone?

Only on the new zone? How is it hooked up to the system? Does it still make the noise if you lower aquastat to say 160*?

john coulson

flashing

Are you pumping away from the expansion tank? what model zone valve? is it on the supply or return?

steve z.

Hot water / Steam

The piping may be wrong, but a quick "patch" is to raise the fill pressure to 20 -25 psi...This will make your boiling point aroung 240 -250 degrees thus eliminating
the flashing...Extrol precharge must be raised as well.
There is a flow problem though....

terry_5

I had this problem,last year!My zone valve were place on the supply side creating the prob,Once placed on return no more prob!

Eric_20

If you are using a zone valve be sure that

you have the flow direction correct, most zone valves will water hammer when they cycle,if they are backwards.

bluemoon

>>>We've located a 2nd circulator in a remote closet in the basement w/2 zone valves serving 2 radiant floors...this zone maybe pulling from the boiler return...then when another zone comes on & feeds cold water into the return...a little thunder storm develops?...system was last renovated 12 years ago...been fine all along...???