is it ok to raise F and E tank vent arm to prevent pumping over ?

[chris1970]

hi,
i've had some modifications to my central heating system in past 6 months and am experiencing some set up problems :

new boiler, new different spec. pump , trv's .

i have been commissioning it myself basically because the installers aren't interested,

i have noticed air collects and it was pumping over when the pump is set to fixed high speeds and the upstairs trv's set low or off.

i removed the downstairs trv's raised the expansion vent arm from 35cm to 60cm and have run cleaner through the system again which seems to have improved it.

I recently read online that the vent arm should be 45cm for average 2 storey house ?, is it safe to keep mine at 60cm or should i reduce it ?

i have also increased the water level in the tank an inch or two because i thought maybe the pump would perform better, is that a good idea ?

i'm just about to drain the system and refill with water and inhibitor (for the first time) and just wondering if i should put the F and E tank back to normal ?

thanks for looking and any advice welcome

 

[gassafe]

You need to check the cold feed & vent arrangement to see that it's correct.

Raising the vent won't hurt the higher the better within reason! I also keep the water level relatively low in the header tank, but it has to be above the cold feed outlet obviously.

The pumping over will cause air to collect in your radiators, and increase the speed at which it all corrodes! So keep an eye on it & get some good quality inhibitor in there.

 

[chris1970]

hello thanks for reply,
i think the arrangement is normal there's a 22mm vent pipe directly above the boiler on the flow and then a 15mm feed right next to it , they maybe a bit blocked because if i get even a small magnet they attract to the copper pipes ( i may re-pipe that whole area if i can't get the system working correctly).

or i may modify arrangement by capping off the 15mm feed and using the 22mm as a combined feed and vent ?

i am getting air in the system after about 2 weeks , i don't really know if it's from pumping over or the rads maybe rusted inside and also i haven't been using inhibitor recently,

i have just done some repairs and cleaning system currently, i have some fnox inhibitor so hopefully that will improve it..

at the moment the water level in tank is around half way so i'll reduce it to just over the feed pipe so i guess that will help the water in tank expand.

just now i have heard a splurt in the tank and signs of water splash , but i have temp. on boiler high and pump high to try and help the cleaning fluid do its job.

so it looks like the vent is working,

 

[Millsy 82]

Really you need to find the reason it is pumping over. You say you have a new pump installed what make model is it? As above the cold feed and vent could be wrong which will cause this?

Why are you not insisting the installer comes back to set the system up correctly.?

 

[townfanjon]

As the lads have said , you must sort out the vent / feed /pump location , it's called 'close coupling '

 

[chris1970]

hi,
i had a new boiler fitted last summer and the company who did that aren't interested in the original pipework or my problems i have called them in once and they really aren't going to do anything.

when they fitted the boiler and insisted 6 trv's had to be fitted teh system was struggling to get downstairs hot so he suggested increasing the pump speed , we set the pump to max but the bearings were making a noise and he said it needed replacing,

the pump was a wilo smart 60 and i have replaced it with a grundfos alpha2L 50-150 , at the time i didn't realise that 50 stood for 5M and 60 for 6M so maybe i have under rated the new pump ?

the property was made in the 80's and it's not very large with boiler in middle of house and airing cupboard directly above and tank directly above in loft.

new boiler is worcester 15ri and pump is directly above in airing cupboard with Y 3 way valve.

in november i cleared out the tank but i checked it last week and it's filthy with brown water and rust filings .

i'll drain and flush a few times and put some inhibitor in and see if i can bleed all air out and see what its like,

maybe i will get someone to replace the pipes around teh boiler and feed and vent T's in the summer , also i can take teh downstairs rads off and clean them like i've done with teh upstairs ones.

my gut feeling is that there's a problem but i'll test it with inhibitor and i'll reduce the boiler temp.

as for the pump i think i'm on teh right setting now i'm on variable no 5 designed for trv's.

the pump has seven settings 1,2,3 fixed and 4,5 variable and 6,7 variable.

one thought i had is maybe if there's too much water in the tank that will make it harder to expand and maybe the water in vent pipe will expand first ?

i think tomorrow i'll remove the cleaner and set the tank level back to where it was.

thanks for advice.

 

[Millsy 82]

Putting a smaller pump in shouldn't really cause it.

Can you upload a photo? Of your pipework in the airing cupboard as that would make life so much easier.

 

[chris1970]

hi
i can't add photo for some reason

in airing cupboard there's a 22mm flow pipe from boiler going into pump then into 3 way valve , when boiler was fitted they fittted a fernox magnet filter after teh 3 way valve.

the vent and feed pipes are under the floor , but i have removed a section of ceiling from the kitchen ceiling ,


the new boiler got moved 6 inches to left so the vent pipe doesn't go straight up into loft as before there's a couple of elbows and piece of horizontal pipe - is that a bit dodgy ?

 

[AlexGas]

...thanks for looking and any advice welcome

I’d say, you’ve done enough, good job, Chris. Why not get a plumber in!?

 

[Millsy 82]

Me personally I would look at repiping the cold feed and vent. I would also look at moving the magnaclean if it's after the 3 port valve (although having one on the system is better than not).

Ideally you want the magnaclean on the return to the boiler but sometimes this is not practical/ possible so as long as all the water passes through it then it will still do it's job. So really if say probably repipe the airing cupboard a little bit so you can get it all piped up properly.

It may be a bit much for a diyer (no offence, you may be able to do it) if you don't feel confident about it then why not put up your location on here and someone on here may be able to sort you out.

 

[chris1970]

hi,
yes i probably will get the pipes re done from boiler to pump in the summer because i've already got large hole in ceiling above the boiler, is it worth just duplicating what i have ? or is a combined flow and feed better ?
if same will get two 22mm Tees put in one for vent and one for feed and then step feed down to 15mm a few inches up (that may stop it blocking in the future ?).

most of my pipes are in the floor spaces so re locating the filter maybe difficult but i will try because i am worried about rust and fillings getting into the boiler and pump, ( i hope the boiler and pump are designed to allow debris to pass through well ).

i clean the filter occasionally but don't get much from it , but during december i had a load of rust etc in teh tank from pumping over , i hope it's just from the pipes around boiler and not fromt he rads and now the boilers full of the stuff too.


i am planning to get some plastering done so i'll remove the downstairs rads and clean them with a hose outside and belt em with a rubber mallet , same as i did with the upstairs ones last summer. with hinesite i should have done all this before the new boiler went in.

i think my pipework is laid out quite well from what i gather , it's 30 years old and i'm sure it hasn't been pumping over for all that time but i don't think its had inhibitor in much so teh rads must be rusted.

i will need a pro to do the soldering and it need servicing so i'll get that done at same time.

i do keep hearing air in the water side , i think maybe the pump is pushing the air around too fast for it to go up into the bleed valve , would it be an idea modify that too ? maybe i should just close the valve down to slow teh flow up but i'm worried about putting pump under strain is it's diverted to water only,

i was thinking to add a auto vent in somewhere but if it's pumping over causing teh air i need to cure that first.

thanks again have a good one,
chrid

 

[AWheating]

system should have been flushed out when the boiler was installed?

an auto air vent near the pump could be a good idea.

 

[chris1970]

hi ,
yes the system was flushed with water a couple of times and installer did run cleaner through it for about an hour just before replacing the boiler but i'm still getting rust debris, but generally the water has been fairly clear.
i'm a bit worried if i run this cleaner through currently too well i'm just filling the boiler with debris - i'll find out how dirty the water is tomorrow with teh cleaner in.

when i get it serviced is it possible to get the boiler emptied out or does the debris flow through ok ?

i'm thinking to re-position the fernox magnet filter to the return pipe just above the boiler in the kitchen - would that be better ? or maybe it will be too close to the ceiling and need covering up and difficult to get to ?

if i leave the filter where it is i could possible replace the bleed valve on the filter to an auto one ?

i read that putting auto vent near a pump can cause it to vibrate and actually add air ? is that just with old pumps because mine runs smooth and silent at the moment - are there any differences in the bottle auto vents - any recomendations ?

i'm going to run the boiler as hot this weekend and try to encourage pumping over by shutting upstairs rads off - i have lowered the vent arm and hopefully will clean the vent pipe at least - i have put a sock on the end of the vent to catch any debris - in december debris came out approx. 2 large spoon fulls .

i'm also getting quite alot of slime in the tank - is that normal and ok ?

thank you

 

[AWheating]

Auto air vents are supposed to be fitted next to the pumps tbh.

filter will only protect the boiler well on the primary return

Do you have a radiator always open? Maybe you could fit A auto bypass on the system, set up correctly it would ensure a min flow rate around the system when your cylinder and try's shut down.

 

[chris1970]

hi,
when boiler was installed i had trv's everywhere except hall where room stat. was, but it was pumping over loads etc.

the room stat. was playing up too in a draft so i found it was more stable in the livingroom so i removed all trv heads downstairs. but it still pumps over sometimes.

the bathroom rad is the closest to pump (approx . 1.5 meters away) and it has a trv on it but i removed the head when i learnt that it's probably used as the bypass and also the door opens onto it causing it to close too quickly.

so now i just have trv's in the 3 bedrooms.


today i have closed down the bathroom rad and all upstairs rads are off because i'm trying to make it pump over , the boilers set high and pump on fixed max.

i have put a sock over the vent pipe to catch any debris and see if it's pumping over and it's done it once in last hour.

i guess i'll monitor it for next few hours and see if it's doing it often then i'll reduce the pump and see if it stops ?

i was wondering if the more rads are open to the system the more expanded hot water will be in the system so it will pump over more because the vent pipe will be fuller ?

or does it pump over more because the pump struggles to push it just downstairs causing it to push up the vent pipe ?

i don't think my rads are sludged up because there's no cooler spots in the middle. but i think they are rusted inside because i didn't use inhibitor for about 7 years and rust keeps flaking off.

is it a problem if it pumps over a few times a day ? with inhibitor in will it prevent oxygen being created ?

if the problem is the pump is set too high for the system flow then surely when the 3 way valve is set to hot water only it will pump over alot ?

i will balance upstairs once i've finished cleaning - should the bathroom rad be fully open or will that rob heat from downstairs too much.

the bathroom rad i need to take off when drained because it has a dodgy lockshield on one side and trv on other , so i'm going to fit two new lockshields on both sides.

 

[Mike Jackson]

The system should never pump over. In can be caused by incorrect pipework, partial blockage, pump speed too high etc. The system should have been flushed by the installer when the boiler was replaced. They have voided the warranty on the boiler by failing to carry this out as well as being in breach of the building regulations.

 

[chris1970]

thanks for reply,
yes they did run cleaner through it before installing new boiler but only ran it for an hour or so and i have a feeling they didn't fire up the old boiler because i had problems with it .

it has splurted and pumped over twice this morning when i heated house up (pump set to fixed max and all upstairs rads closed) , i will keep the boiler temp the same and set pump to variable and see if it pumps over again.

then tomorrow i'll open the upstairs rads and do same tests again.

monday i'll drain and put inhibitor in and use heating system on lower settings and see if there's an air problem and any pumping over.

 

[chris1970]

well i drained the cleaner out and it was clean, but i remove the bathroom rad to swop the trv for a lockshield and it was filthy inside, so i cleaned it out by hand and had sludge etc inside.
so i took off two of the downstairs rads and they were just the same.
i don't know if the trv's reduce the flow and prevent the cleaner from working or my lockshields but was a waste of time putting that cleaner in for a week.
maybe i have blockage somewhere affecting the flow but the bathroom rad is very close to the pump , or perhaps i will re-pipe the feed and vent area.
i'm fitting all new lockshields and just having trv's in the bedrooms which i cleaned out last summer.
hopefully all should be improved .
thanks for the advice

 

[SimonG]

Did you turn the boiler stat to max. The cleaner likes heat.

 

[chris1970]

yeh i had it set to 3/4 for most of the week and once on max for few hours just before flushed out.
it's almost like it never even went around the rads but they were getting very hot.
i'll finish cleaning by hand and with all new lockshields the flow should be much better so i may run cleaner through again.
looks like they aren't rusting just some sludge and lot of black coming out.
i'd be supprised if the feed and vent are blocked but i may re-new anyway and re-position teh magnet filter above the boiler on the return pipe at the same time.
just two more rads to clean and fit new lockshields but i have got a leak on one of the drain points , is there a washer or something inside i can replace ?

 

[PhoenixServices]

Yes you can buy washers for in the drain offs. Any good merchant should stock them. Or just buy a whole drain off and swap the guts.

 

[kay-jay]

sounds like feed and vent arrangement is ok.

however if a magnet attracts, then you have a blockage, if theres a blockage you have crud in system, if theres crud in system you have bad circulation, if you have bad circulation you get pumping over. if you have pumping over and a blockage on the feed then you get pockets of air.


raising vent will adress symptoms and not the cause.



QED

 

[kay-jay]

p.s before circulating cleaner of any description you should have opened all lockshield valves fully.

 

[chris1970]

yes i opened all lockshields fully and removed the trv heads.
all rads will be cleaned by hand after today and i'll see if any improvement but i think i'd like to renew feed and vent anyway in the summer and run cleaner again to try and clean the pipes.
would it be an idea to poor boiling water down the vent and feed pipe because that seems to clean the rads well.
cheers guys,

 

[chris1970]

hi,
thanks again for the help and advice ,
everythings back working ,
maybe i didn't use the cleaner properly next time i will run it as hot as possible and make sure i don't have it running through the water side at all.