improving pipework for feed and vent

[chris5346]

hi,
i've had someone look at my heating system recently and he wants to combine the feed and vent pipes to help eliminate the air and other problems i have been experiencing over the last year following a boiler and pump upgrade.
he also wants to remove the vent. arm above the F and E tank which i'm unsure this the right thing to do ?
here's some drawings of my system and possible modifications:

the system is 35 years old and a Y plan, i don't think it has a bypass valve fitted.
there are 8 rads. with just 3 trv's fitted in the bedrooms,
the boiler was upgraded several years ago along with a filter and new pump.
i have had many problems , my main concern is air getting in the system also in the winter i'm having to continually adjust things to keep it running.
i have done everything i can to the rest of the system so now i'm thinking to improve the pipework around the boiler,pump and improving the feed and vent ?
please advise ,
chris

 

[bernardgreen]

Feed and Vent......... Two very different functions. Hence two different pipes.......

i've had someone look at my heating system recently

Who was this "someone" ? Is he a plumber ?

 

[picasso]

I would go with 3 or 4 but move the filter to the return.

 

[Nige F]

4 and leave the filter because there don't look like room for it on the return. Has the boiler been fitted with the F+R correct ???? not unknown for them to be swapped

 

[chris5346]

good morning and thank you for your replies,
i'm 99% sure the F & R are the fitted right way round but i will double check when the ceiling gets cut away more to replace the pipework, the guy that came round is a working plummer, but he has never worked or seen mine before.
the stage i was at last week was thinking that i have a leak somewhere pulling air in, so i got some F4 leak sealer to put in but he thinks a reconfigure is the way to go.
i would prefer not to move the filter because it will end up very close to the boiler and will be difficult to access when i fit cupboard in etc, but i believe they protect the boiler better that way and also if i do that maybe one day my airing cupboard will be free of equipment if i remove the emersion tank and move the pump abit (thinking to get an instant water heater if i still have problems with heating system).
what about leaving the elbows on the returns ? will that affect the flow much and getting heat around the system etc ?
in the coldest of winter the boiler usually trips off on over heat and i'm having to set the pump to higher speeds but that makes the air problem worse.
the filter is in a good position to collect the air , very rare i get much out of the rads. these days but i currently have to bleed it everyweek.

 

[jeff the gasman]

Have you checked for magnetite blockage in the existing pipe work? This would cause all your symptoms.

 

[bernardgreen]

If the air is believed to coming into the system from the vent pipe then as a trial fit one of these to teh end of the vent pipe over the tank.

http://www.hepvo.com/

This will allow the system to vent but will prevent air being drawn down the vent pipe.

Does the boiler have any air bleed valves in it or between it and the pump ?. Some of these, especially the automatic ones, will allow air to pass backwards through them and into the water when the water pressure at the valve is less than atmospheric pressure outside the valve

 

[picasso]

Your system is a bog standard y plan so I am bit surprised your "plummer" has not see yours before, if your pulling air in I would check the feed is not blocked before changing pipework.

 

[chris5346]

hi,
yes if i get a magnet there is a small attraction to it at those tee's but i don't think they are badly blocked ?
what about not having a bypass valve ? are they just a safety thing or do they help the system work better ?

 

[chris5346]

sorry what i mean is the plummer hasn't been to my house before and he's unaware how bad it is in the winter and knows about all the faults i have experienced.
how would i check the feed insn't blocked ? if i'm cutting any pipe in that area i may as well renew and improve it at the same time.
i think i'll do no . 4 modd and see if it's any better this winter,
i'm also thinking the boiler is a bit under rated so maybe i should remove the hot water side and keep boiler just for heating - it maybe easier for me to set up and remove air etc,
we don't fill a bath very often and have electric shower so i'm thing to get a high powered instant water heater for kitchen sink and single bathroom.
also my airing cupboard is huge and the extra storage space would be useful or maybe fit a second toilet.

 

[chris5346]

no the only air bleed valve is in airing cupboard after the 3 port valve on the water side, i usually keep the water side switched off and heat water with the emersion heater to stop air going around the water side and back into the boiler.
the plummer that came round said i don't need a vent pipe as longs boiler has over temp. and the water in the F & E tank is kept low.
if i do the modd no 4 is it better to relocate FE tank to make 4a or is a 40cm piece of horizontal pipe ok ?

chris

 

[chris5346]

 

[Hugh Jaleak]

I'd cut out and replace all the pipework where the magnet is attracted before doing anything else. You may be surprised how 'not badly blocked' they are! Its definitely air you're getting out the rads? (Not hydrogen!) What inhibitor is there/has there been in the system?

 

[chris5346]

hello, yes good idea , well for many years i had a very old boiler and don't think it even had inhibitor , but then i had the 15Ri and many trv's fitted 2 years ago and installer put in Fernox f1 , the system didn't work well from the start , pumping over air in system and boiler tripping off etc , fitter said to set the pump to max. but the old pumps bearings were noisey so i fitted a better pump myself a few months later , i have been removing trv's and fitting new lockshields etc and i removed all rads. and cleaned them by hand, the pumping over and air in system is better but not perfect, also i think when it's very cold the boiler will struggle to stay on for long periods of time.
one mistake i did make last year was not to put inhibitor back in and just 2 weeks later the water had turned dark brown and mayonese type stuff in the filter etc, so i cleaned it all again and added inhibitor though this summer , i'm not sure the current state of the water , i want to do this modd and test the water before i use the system this winter .
this time i will keep the water and re-use it.
i've never done the hydrogen test,
there was some black sludge in the downstairs rads. but they cleaned up ok .
the rads do get very hot with no signs of cold spots but the boiler trips off on over heat in feb. - my feeling is the boiler is underrated and 22mm pipes with those elbows don't get the heat around fast enough , or maybe there's a blockage where your suggesting .
i've also got a complex room stat. which seems to switch on and off when it shouldn't , so i never know if it's the room stat. and or the boiler over temp. but i get air in stytem which is my first worry.

 

[chris5346]

i want to be able to run the pump fairly fast so the rad. in the hall gets hot (last one on run) , i haven't really balanced the rads. much because i'm worried about restricting the flow incase it makes more pumping over, i also don't think i have a bypass valve so a bit worried about safety.
what does seem to happen is the return pipe to the boiler gets hot quite quickly before the house gets upto temp. - maybe the heat goes through the bathroom rad. and back into the boiler too fast causing boiler to over heat a bit ?