central heating problems

[chris5346]

I had a replacement boiler last year (worcester 15ri) and just started using it,
there's tapping noises and banging pipes etc so i have got some fernox F2 to try and improve it.
i have also noticed i'm having to bleed one rad often and looks like air's getting in , so i have tightened all rad connections,
i did have a leak on the gatevalve heating the emersion tank just after the 3 way valve which i repaired using ptfe tape.

i'm just about to flush system and add some F1 and F2 but should i replace that gate valve or maybe just put straight pipe in ?

what's that gate valve for ? should i be reducing the flow of central heating water through the emersion tank ? or is it always left fully open ?

in the summer i also replaced the pump (had wilo smart pump and replaced with grundfos alpha 2L).

because the upstairs is noisy i have been closing off the bedroom rads but the boiler seems to be struggling , i set the pump to max to try and get the downstairs hotter but seems to draw more air in and make more noises somewhere.
so i have set the pump to fixed 2 which seems the best.
i've also been adjusting the boiler temp. and just under half way seems ok ?

i went up into the loft to see if any pipes were touching or rubbing each other and i noticed that two times water splurted out the expansion tank vent (i did set the boiler to over half way so maybe that caused it ?)

please any advice welcome i'm going round in circles trying to improve it,

house is 2 storey early 1980's seems to be standard open vent heating system .

i also had trv's fitted at same time as boiler.

downstairs everything is working well.

sorry about all this info. i'm basically wondering if i can remove that gate valve or do i need it to reduce flow through the emersion tank , also any other tips appreciated.

thanks for looking, chris

 

[kbdiy]

Banging noises usually indicate air in the system. Not likely to be rad connections as these would show leaking water first.

The pumping over (water from vent entering the header tank) would suggest a blocked cold feed or possible incorrect pipe configuration. Check with a magnet where the cold feed joins into the system pipework. If it sticks then you have found the blockage - magnetite. The pipework will probably need to be cut out and replaced to remove the blockage.

 

[jackthom]

There's a bit more info about pumping over in the FAQs. It's not good and should really be sorted out before anything else.

//www.diynot.com/forums/plumbing/faqs.37170/#p_891831_message

 

[chris5346]

hi, thanks for reply,
funny you should mention the cold water feed maybe blocked, when i drained the system to replace the pump there was a lot of muck and slime etc in the expansion tank so i cleaned and washed it all and some went into the system , maybe its bit blocked.

i was also wondering if my boiler is underrated , i used to have an old olympus maybe 18kW and now i have 15ri, the boiler seems to switch off on overheat ,

if i open the upstairs rads and set teh 2 way valve to middle position the boiler seems happier and can continue to get downstairs heated.

what about the flow through the emmersion tank ? is that important or can i replace that gate valve with piece of pipe ?

 

[kbdiy]

The gate valve is there to allow you to reduce the flow through the cylinder coil so that the hot water circuit doesn't rob all the heat when you are running the central heating at the same time.

Forget the gate valve for the moment. You need to concentrate on getting the heating to run correctly without pumping over or filling with air (which could be one in the same problem) first. Try the magnet test.

The tapping noises you mentioned could be tight pipework where it passes through floor joists etc. Sort the main problem of air first then do the rest later. This is not the time of year to have unreliable heating.

 

[chris5346]

hi, the water part always seems to make bubble noises and can hear the rushing water when 3 way opens to water so i thought maybe that gate valve still had tiny leak and drawing air in,
there is a bleed valve near the emersion tank and 3 way valve but that doesn't see to collect much air.
air collects in the bathroom rad , maybe had a inch of air on top after running heating for a week.

the past month i haven't had any F1 in it so i was thinking maybe rads are giving off some oxygen too ?

i have some F2 and will get some F1 soon but i was thinking to drain system and fix things first,

i will check that joint today with a magnet but not sure if i can get to it

i was wondering if the pumping over maybe caused from the trv's now fitted and i'm trying to reduce the flow through the upstairs rads because some pipes are touching the floor boards.

there seems to be several noises it's making.

what about the pump ? there's 7 settings on it, 3 fixed and 4 variable , i have been experimenting and variable doesn't seem to get the heat round fast enough, maybe fixed 3 is drawing more air round and making more noises so i have selected no 2.

is it worth adding some F2 now and maybe it will improve the heat transfer ?

the boiler is basically new it was replaced last spring and switched off /drained all summer while i had upstairs rads off and pump replacement.


when the guy replaced teh boiler he only stayed 30 mins to test it, as soon as rads got hot he went,

the house is the size of a 3 bed semi with 5 double rads and 3 singles in the bedrooms , i think either i have a blockage or the boiler is under rated .
i was hoping if i uprated the pump it would improve things.

i'll see if i can find that cold water joint.

regards

 

[chris5346]

just been into loft and looked at expansion tank ,
the water outlet is 15mm and doesn't drop straight down it goes about a meter with several sweeping 90 bends then drops down behind the emersion tank into the floor space , so somewhere there will be a 22mm with 15 Tee ?

the water level in the expansion tank is quite low just under half way is it worth me raising that to nearer the top ? i notice there's an old water mark higher up maybe i have bent the ball float or other guy lowered it ?

could the pump be cavitating and raisng the water level help it ?

i can cut away some of the kitchen ceiling and try and find the 15mm to 22mm feed connection or should i try these additives and repairs etc ?

maybe its just my boilers underrated and struggling ?

i think i did have the gate valve for the water fully open so maybe that's robbing the heat and hot water is going back into the boiler return pipes hot causing the boiler to switch off on overheat.

another worry is have a fitted the pump backwards, i can't remember what the old one looked like i just assumed they all pump upwards into teh 3 way valve , could the 3 way valve and water part be on the return pipes ?

 

[kbdiy]

I can only comment based on my own experiences but let me give you a comparison with my own system.

I have an open vent system with a conventional (10 yrs old) boiler. I did suffer from pumping over but found a blockage where I described (common problem), cleared the blockage, flushed the system, replaced the pump (same model as yours) and it runs like a dream. Pump is on max fixed setting, no pumping over or air problems. I run my pump on max as I have several long old rads which heat up better on that setting, otherwise the centre can be a bit cool. Mine is a large 1930's semi.

My conclusion regarding your system is that you need to identify if there is a blockage and sort that first. Then flush the whole system. I don't believe your boiler size would affect the pumping over problem so at the moment that is a red herring. Then I would be checking how well the new boiler is venting - is there an autovent and is it working correctly and/or how does the new boiler connect to the open vent? It sounds like the boiler replacement was done in a bit of a hurry if he only waited 30 mins to feel the rads heat up and then ran.

 

[chris5346]

the 22mm open vent pipe and 15mm feed connect to the pipes just above the boiler but i can't get to them to try a magnet.

what do you mean by boiler venting ? there's a plastic condensate pipe at the bottom of the boiler going into the stack but i don't know if that's working well or not ?

the pumping over may have been just that one time when i set the boiler temp to over half way nearly 3/4 i was trying to heat the pipes up quickly to hear for noises but maybe i set it too high and with air in the system and the trv's now fitted the pump couldn't push the hot water around fast enough ?

i could probably remove the trv heads and the system would work better apart from the pipes rubbing on floorboards and air etc.

i should really try to get the thing working with plain water then add additives ,

the boiler seems to perform better when i remove the air but there still seems something fundamentally wrong.

i'm not sure where to start now , as i said i keep going round in circles, i think the air in system seems first thing to fix ?

other problem is i don't know what the system was like before this new boiler , i can remember teh old boiler being noisy so maybe it drowned out the noises i can hear now..

 

[kbdiy]

Can you post some pictures of the pipework, boiler and controls? That might help in explaining where to focus first.

 

[chris5346]

yes will take some pics but not much to see because almost all the pipes are in the floor space,
in the kitchen all have is two 22mm pipes for the flow and return to the boiler ( boiler was moved 6 inches and they just put some horizontal pipe in with 90 deg elbow (not sweeping )which i don't like.

the emersion tank, pump, 3-way valve and new magnet fernox filter all directly above and water tanks above those in the loft.

they fitted new boiler and vent goes thru the outside wall and there is a hole in the kitchen ceiling where the vent used to go up , but unfortunately there's a noggin where the expansion tank pipes connect up , i think i'll take some more ceiling down and try the magnet test.

or i can try fixing any leaks and try the F2 first.

the downstairs rads will get very hot but the boiler shuts off before the thermostat gets upto temperature, it struggles when the house is cold and trying to get from say 14 deg to 19 deg , if it's already 17 then getting to 18 or 19 isn't as bad.

i also dont know what's going on with the remote thermostat sometimes it's calling for heat when it shouldn't , it maybe too close to the front door or when walk past it seems to go funny.

when it's left alone it does seem to switch on and off ok .

 

[chris5346]

http://medi//media.diynot.com/225000_224506_86231_19713993_thumb.jpga.diynot.com/2http://media.diynot.com/225000_224506_86234_61200592_thumb.jpg25000_224506_86230_26818358_thumb.jpg

 

[chris5346]

i'm struggling to add photos , i have put some in my album

 

[chris5346]

//www.diynot.com/network/chris5346/albums/

 

[chris5346]

hi,
so i have located the 22mm vent and 15mm feed where they connect to the flow from the boiler and they do attract a magnet , not just the t connectors the pipes in that area too.
as mentioned the boiler has moved 6 inches to the left so the vent doesn't go directly up from the boiler anymore it goes through two 90 elbows , is that a problem or should i put a new 22mm pipes in closer to the boiler.

is combining the vent and feed as good ?
how's that done ?
can i do this in plastic pipe ?

thank you for advice so far,

chris