I need you knowlage!!!

[ADM360]

I'll try and keep it brief!!

I have inherited a heating system with a new customer.

First job kitchen rad not very hot! every one else lovely, add cleaner allow to run for about 10 days, spend one day balanceing entire system and fit new 15-60 grundfoss pump.

all good, all rads running nice and toasty and quite quick too.

But new problem!! when the heating shut off the F+E overflow starts to run, turned pump back to 1, still happens, checked F+E and standing level is just under overflow outlet. but when heating is turned the level in the F+E drops buy as much as 2" which is then topped up to original level and when pump shuts off the vent dumps the original displaced water back into the tank overflowing!!

as a temperay messure I have adjusted the float valve down to allow for expansion, but its the pumping over though the vent that is bothering me!!

both the vent and feed are clear as I have check both, the flow comes from the boiler, up though the floor of the airing cupboard up ot an elbow across to elbow and down to the pump, on the horizontal is the vent and feed over 150mm from the pump. Vent, feed then pump.

Help please!!!

 

[SimonJohns]

Abv needed

Should prevent pumping over

Sounds like you have a boiler with pump overrun?

 

[Mike Jackson]

Raise the height of the open vent. Also what system is it? If it's an S plan with no bypass when the valves shut there is nowhere for the surge of water to go. What pump did you replace?

 

[ADM360]

Should have added, it is a Y plan, there is a manual bypass but I have almost shut it as there are two other heat leak rads in the system, yes there is pump over run, and no I can't add height to the vent as it run up to the ridge board, the loft space is very cramped!!

I did wonder about altering the feed and vent to a combined! or an air seperator! or dropping feed and vent down further from pump!! or some thing!!

Thanks for your help!!

 

[ADM360]

also, replaced 15-60, so did a like for like, although in hindsight a 15-50 may have done!!

 

[Mike Jackson]

A combined will do the trick but check the MI for the boiler as some manufacturers don't like it with their boilers.

 

[ADM360]

Think its a vokera from memory!! thank again for your help!! now to tell the cutsomers that the guy that fitted it got it wrong!!!

 

[Billy Bob Bob]

Raise the height of the open vent. Also what system is it? If it's an S plan with no bypass when the valves shut there is nowhere for the surge of water to go. What pump did you replace?

with mike on this one,the other alternative you have if the boilers suitable convert to a sealed system

 

[ADM360]

Thanks gasman, but I think we've covered those points!!!! would if I could but can't!!!

 

[Billy Bob Bob]

Thanks gasman, but I think we've covered those points!!!! would if I could but can't!!!

why? cant see a sealed conversion mentioned in your posts if the boiler has a high limit stat its suitable but you need to consult the manufacturer first

 

[ADM360]

Sorry missed that one!! but again got to tell the customer its gonna cost to put right what should have been done first time round, so simple / cheap would be best!!! ( I know niether of them are often the best option) thanks for your thoughts gas man.

 

[jonmanty]

If you can't get the height over the top of the cistern to prevent surging. Common approach is to form a surge arrestor in the vent pipe usually from a 54mm short length of copper about 400mm long with its mid point at the cistern water line or thereabouts. Reducers on either end down to 22mm. The increased volume in the large section of pipe should be sufficient to take up the surge and prevent the discharge over the vent.

Jon

 

[stevetheplumber]

id change the pump for a 15/50

 

[bengal lancer]

Sounds like a pipe work issue. Look at the 3 tee rule from the boiler . sounds like they spured a radiator for a extension maybe in the wrong place at a guess.