Help! - Noisy central heating system – not heating water well ……

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Discuss Help! - Noisy central heating system – not heating water well …… in the Central Heating Forum area at PlumbersForums.net

here is the pipework around the pump and the motorised valve.
its hard to get in there to get a decent photo that captures everything clearly without one pipe obscuring another - but i have


labelled
boiler pipework.JPG
where they go in the hope that it helps
 
No, if I understand it correctly the F/E pipes are positioned as such that it can't but help suck air into the system, usually they're positioned differently and behind the circulator (pump) . There should be a pipe feeding the pump from beneath, where's that coming from because that should be coming from the boiler and the pipe you've labelled "To boiler " going to radiators.

boiler pipework.JPG
 
hey, thanks for your input !👍

i have just checked the pump direction and i do believe its direction of flow is in the direction you indicate. i couldn't find any arrows on it - and there is nothing in the user manual - but the shape of the casting shows the fitting at the bottom goes to the centre of the impeller scroll - so its sucking from the bottom and pumping upwards

in terms of air getting "sucked in" through the expansion pipe - what i don't get is that the water feed and expansion take off both appear to be on the "high pressure side" of the system.
by high pressure i just mean that the coil in the hot water tank are downstream of the expansion pipe - so to my novice brain - i would have expected the circuit to be boiler - pump - expansion pipe take off point - coil in hot water tank - back to boiler

so assuming there is some restriction due to friction in the coil in the hot water tank - on starting the pump i would have expected positive pressure at the point where the expansion pipe is taken off - so i would have expected it to try to push some water up - at least a little against gravity - rather than draw air in -

what am i missing / do i have it wrong ?

will add a couple more photos in case it helps

mot valv and bypass.JPG
pump lower.JPG
 
Have a google of any open vented diagram, the F/E pipes are always behind the circulator on the circuit and never in front, that is the cause of your air ingress issues.
 
gmartine said:
Have a google of any open vented diagram, the F/E pipes are always behind the circulator on the circuit and never in front, that is the cause of your air ingress issues.
Click to expand...
Thanks again

this is rather frustrating - seems like i have inherited someone's shoddy work ....

i have had a quick google and found there are examples of both ways though

the system does not do it if on central heating central setting - only on hot water - why is that ?

and does this suggest it might be possible to run this configuration and tune the problem out somehow - maybe by fitting a restrictor or something ...?

or is the only solution re-plumbing the F/E to alternate locations ?

thanks again for your help!

open vented 1.JPG
open vented 2.JPG
 
Actually the later example shows the feed pipe is nearer the rear of the circulator than the front on the circuit. Still I don't think it's a reliable example (DIY website) , needs replumbing.
 
gmartine said:
Actually the later example shows the feed pipe is nearer the rear of the circulator than the front on the circuit. Still I don't think it's a reliable example (DIY website) , needs replumbing.
Click to expand...
OK - i am following you - thanks for the explanation - will have to have a think about how i could replumb the pipes in practice

or - if going that far anyway -

it may make more sense to redesign the system to be a closed boiler circuit system - and also create a mains pressurised hot water circuit - as hot water flow / pressure is currently too low for an effective shower upstairs - and i was going to install an additional pump for that purpose -

but installing the appropriate expansion vessels and regulators would achieve both .....

its a big job for me in my current state of health thou - and don't want to be without heating all together for long in the middle of winter - so will need to give it some thought....
 
Last edited:
Sealing the central heating circuit should alleviate all your current problems. Cap the F/E feeds, add an expansion vessel and filling loop shouldn't cost too much or take too long to have done.

You can't pressurise an open vented HW cylinder but adding a single or twin shower pump should be straight forward enough.

Good Luck.
 
gmartine said:
You can't pressurise an open vented HW cylinder but adding a single or twin shower pump should be straight forward enough.
Click to expand...

thanks

i had wondered about that - my guess is the system was installed around 12 years ago - probably just before pressurised systems became the norm - there are no pressure rating markings on the HW tank - so i guess it is the non-pressurised type
shame

will go with the pumped shower solution - think i just about have room to install this and a pressure vessel in the airing cupboard

ref the expansion vessel for the boiler circuit - is there a rule of thumb i should follow for the size i should use

i guess its based on volume - the system is smallish - 5 radiators and the HW tank coil - smallish 3 bed house
2x 6ft double layer radiators
1x 3ft double layer radiators
1x 6ft single layer radiator
1x 3ft single layer radiator

any other gotcha's i should look out for

thanks again !
 
If it's a 60's house chances are you don't have the water pressure and flow rate to be able to utilise an unvented cylinder anyway.

An EV is usually based on 10% system volume'ish so an 8 litre EV would do for a small system.
 
have ordered a 12litre EV and install kit to err on the safe side - plan to install it in the AC above the HW tank - directly into the lines that currently go up the wall into the loft to the expansion tank.

was very reasonable - here -
www.unventedcomponentseurope.com

Altecnic - ERES 12 Litre Heating Expansion Vessel & Sealed System Kit ER-12LTVESS

Altecnic - ERES 12 Litre Heating Expansion Vessel & Sealed System Kit ER-12LTVESS
www.unventedcomponentseurope.com www.unventedcomponentseurope.com

do i need anything else ?

anything i should watch out for ?
 
yep - the F/E pipes

i see the instructions say preferably on the return side - but doesn't say MUST - so i m hoping that is not essential

as i understand it as long as the system volume is able to expand unhindered into the vessel - then it will work correctly - and since no air can get sucked in via the vessel - that should solve the air issue

no?
 
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