central heating pumping over!

[benny_headland]

hiya guys

im a 3rd year aprentice , iv been working at my brothers house for the last fuw days repaceing his old 8mm microbore manifold system to tidy it all up a bit....

the boiler was constantly over heating and tho flow to the radiators was just ****! and the pipework was very untidy so i just replaced it all with 15 mm and 10 mm to most the rads.....

--> basicaly the vent for the f&e tank use to pump over and after all the change over still did so until the system got hot and then it stoped?

i have photos for you to look if you can see anythying wrong that im not aware of :/

was wondering if the dinstance of the cold feed and the vent was too close?

would fully appriciate any help thanks

ben.

 

[benny_headland]

i have turned the pump down to the lowest setting aswell and it still trickles out the vent

 

[benny_headland]

another photo

 

[Billy Bob Bob]

boiler over gassing,system debris(blockage)system design all these need to be checked is the pump working?

 

[benny_headland]

yes iv only just replaced the pump and its defo working, the whole systems gets hot quick enough.....and im pritty sure its not a blockage !

its only trickleing a lil bit.... and seams to stop when the system is hot :/

 

[Billy Bob Bob]

get some one to check the boiler out,could be over gassing or thermostat failed what boilers in there? need to check mi,s see if system install as per mi,s as some ask for vent and f+e design specifics

 

[diamondgas]

Hi Ben,

Thanks for the photo's.. First thing i see is a really poorly positioned vent pipe ... 'bubbles' don't go sideways! So the system will struggle to get rid of it's 'air'. As 'gas man' says, check out the manufacturers instructions. They'll give you good advice regards positioning of F&E pipes. ... See if you can combine them. Rule of thumb; if the boiler has an overheat stat and pump overrun they'll allow combined f&e. Check them out.
Big concern would be how long has this been allowed to pump over B4 being recognised? Longer its been allowed to go on, the greater the potential for grief!!!

 

[steosman]

do away with the f&e tank, connect onto mains water feed(filling loop), install an expansion vessel, manual air vents, and make sure boiler is fully vented.

 

[Billy Bob Bob]

do away with the f&e tank, install a expansion vessel, manual air vents, and make sure boiler is fully vented.

if theres a high limit stat fitted to the boiler,otherwise its not a option

 

[benny_headland]

thanks for your replys guys....

well the boiler is a gloworm micron 40ff

im quite sure all the air is out, it all gets hot and cant hear any gurggleing etc, a ran the pump for a while befor swithing the boiler on to get it all moving a bled as i could!

and im not sure that it does have a pump over run... ? :/

 

[REDSAW]

instinct only tells me its been doing it for a while and some one has altered the vent pipe trying to eliminate it but have failed?.

 

[BLOD]

Check with a really small magnet to see if it sticks anywhere around the cold feed & vent connections under the pump, indicating a blockage.

 

[Plumbcrazy56]

No pump overrun on a Micron.

 

[diamondgas]

Ben, is it possible to raise the open vent pipe. Not the most ideal solution but it works. I've looped vent pipe up to the rafters to overcome pumping over.....! If you can't combine the F&E you could consider an Air-separator? Have you Checked the MI for combining?

 

[marinegmillie]

Hi, vent pipe should be 450 mm above f&e cisten, also cold feed should really be 22mm its this pipe that takes most of the expansion

 

[benny_headland]

Ben, is it possible to raise the open vent pipe. Not the most ideal solution but it works. I've looped vent pipe up to the rafters to overcome pumping over.....! If you can't combine the F&E you could consider an Air-separator? Have you Checked the MI for combining?

no pump over run so im guesin i shouldent be combineing .

yes well i did raise it myself about 450mm, wasent sure how high i could take it? does it really matter if its right up to the rafters? :/ ,

so my options so far are.....

*raise vent even higher...?
*change cold feed from f&e to 22mm...?
*air separator....?

 

[benny_headland]

yano what guys iv just read the manual and realise there is no bypass on the system either!

http://www.glow-worm.co.uk/stepone/data/downloads_sd/8b/00/00/micron-40ff.pdf

also can see some diagrams on section 3 page 9 that im asuming sugest i can join the cold feed and vent aslong as they are both in 22 mm.... ?

 

[benny_headland]

diagram!

 

[marinegmillie]

Wouldn't of thought u need to go any higher than 450mm. Change cold feed to 22mm and connect feed and vent to a airjac (air separator)

 

[diamondgas]

Hi Ben,
According to MI (p9, dia3.2) you can combine the f&v. Probably best done, in your case, using an air separator too as the pipe isn't ideally situated to 'vent' anything, it being horizontal to the pump flow. The combined f&v needs to be 22mm from the header tank.
Incidentally raising the vent pipe higher will overcome the effects the pump is having on the water in the system. It's the pump that's raising the water higher than the 450mm you have at the moment, there is no other component on your heating system that can do that. If the pump is producing a positive pressure on the vent greater than the height of the vent, pumping over occurs. There will be a limit to the height the pump is raising the water within the vent pipe.

 

[washer]

I would cut out and check the pipework isnt partially blocked between the open vent and cold feed where it tee's in behind the pump.

 

[bob the plumber]

why dont you bring down seperate feed and expasion pipes, bring them in behind the pump no more than 150mm apart, i always do it like this and ive never ever had a problem with pump over

expansion, feed, pump, (bypass..S plan), y plan or s plan??