over flowing vent pipe

[daren]

I am currently having problems with my overflow pouring water ever time i try to either put the heating on or the hot water on.
the smaller tank in the loft is reciving a large amount of water returning via the vent pipe, this is a mixture of steam and water.
its over flowing at approx 5 - 10 gallons a minute.

i have had to switch the system of as i am concerned the over flow cannot handle that amount of flow and will flood.
this happens when the heating and hot water is on or also if either one is on seperatly.

The boiler is a 1972 dansemore oil fired df boiler which is serviced regularly.
i have also noticed that the circulation pump has become noisy.
i can also hear water rushing through the pipes this sounds to be a mixture of air and water.
there are air vent valves on the system and these are also full of air.
If i leave the heating on the rads all get hot there does not seem to be a problem with the hot water circulating.
I do not think the hot water coil in the cylinder is leaking as i have tried some of the suggestions in previous posts.
i can also hear water boiling in an around the pipe work near the boiler i have not heard this before

Hope you can help.

Daren

 

[chrishutt]

Sounds like a blocked feed and expansion pipe. Blockage is usually near the junction with the flow or return pipework. Common problem which you'll find lots on if you do a search. Don't continue using the system since it's losing it's water and you're likely to damage the pump and boiler.

 

[fitz1]

had similar problem where thermostat had lost its calorbration.but as above says more likely to be a blocked feed.is tank overflowing or circulating ?

 

[daren]

what the best way of dealing with the blockage?
do i need to drain the system and refill to try and clear it.
how do the rads still get hot if there's a blockage, same goes for the hot water.

thanks

daren

 

[fitz1]

similar problems on here today. try turning boiler thermostat down low and see what happens.

 

[daren]

hi,

tried that yesterday and noticed that boiler would not heat up the rads and boiler switched off before temp was reached in room, what is odd though is if i turn it up to min then the over flow runs ,the boiler has all ways been run with the thermosat set at min or below, tried the stat set at mid way between min and hign slightly higher then normal and the overflow ran much faster more like a hose on full with a huge amount of steam as well

 

[fitz1]

get stat checked

 

[daren]

thanks fitzs will get someone round to have a look, is replacing a stat diy or a corgi job?

Regards

Daren

 

[fitz1]

its a form of control to a gas appliance so its corgi.not diy

 

[ChrisR]

5 - 10 gallons a minute

Does that start as soon as you turn the system on, or only when it has got hot?
If the former than you have a blockage see similar post today, an nowt to do with stats.

 

[daren]

about 5 mins after the boiler fires

 

[lor]

could it be a seized pump, water boiling a nd pushing up vent pipe to f& e ??

 

[daren]

pumps been making some very loud noises, in the time honoured tradation if i give it a thump it stops making any noise.
guess i need to

a) check stat
b) check pump
c) look for blockage

let you all know which it is

thanks for the reply

 

[ChrisR]

5 minutes is a longish time. Slow pump and a dud stat then! If you've been running below minimum on the stat, that sounds faulty, though it should have been picked up on a service.

 

[daren]

just to let you know the pump was knackered and the boiler stat has packed up,

now the hunt begins my boilers a 1972 model and spares are hard to find
thanks for the advice