Is there a plumber in da hoose ?

[johnik]

i put the boiler on at 16-00 for about an hour, if i switch to hot water only, no sound, hot water in the taps, switch to central heating and hot water, it makes a single bang around 10 seconds after switching on, it definatley sounds and feels like it,s the valve, that and the lack of hot water (when switched to HW and CH) points me to the valve....but i know nothing about how these things work

 

[Kayos]

Sounds like the valve as they rest in hw so just switching that on usually works as you describe once they have failed

 

[brightspark]

feel the 2 output pipes from valve when water and heating turned on. they should be both as hot as each other sharing the flow providing the cylinder stat is calling for heat .turn the stat down and all the hot flow should go to the heating side and water side cool down

 

[johnik]

thanks gents, makes sense with no bang on HW only, tried the pipe temp test and the stat is working, time to dig out my waterproofs and change the valve ....wish me luck

 

[johnik]

last thing..promise, i ran the heating a bit longer this evening, felt the pipes and they were all hot apart from the bottom conexion to the coil, that was cold, let about 1 pint of water out of the drain valve on that pipe and it got hot, i know it will be cooler as it transfers it,s heat to the tap water but should it be actually cold ?

 

[Kayos]

Could be the cold feed

 

[brightspark]

Could be the cold feed

looks like it but its in 22 mm so could be the return and feed is somwhere else in 15mm

 

[Tigman]

I used to put a bypass between boiler flow and the return so when the mid position valve closes (both ports) the pump can still pump ! And the cylinder coil return as close to the heating return as possible , where is the pump ? What type of boiler ?

 

[johnik]

Could be the cold feed

looks like it but its in 22 mm so could be the return and feed is somwhere else in 15mm

it,s 15 down the wall and 22 at the tank, it,s deffo on the bottom of the coil.

I used to put a bypass between boiler flow and the return so when the mid position valve closes (both ports) the pump can still pump ! And the cylinder coil return as close to the heating return as possible , where is the pump ? What type of boiler ?

there are some pics on page one of this saga, i am afraid i know zilch about these things, the boiler is an oldish Baxi with no model number, pump is shown in the pics

 

[Tigman]

No pump in pictures I can see ?

 

[Tigman]

I think when heating and hot water are both calling for heat , the pumped water prefers the heating circuit because the cylinder return is 15mm and is restricting the flow so the heating takes priority when the heating is satisfied the water will go around the cylinder coil , that's why it works when it's hot water only , have you a room stat for heating ? , if you fire it up feel coil return see if it's cold , then turn off the room stat then feel the same coil return if it gets hot straight away , puzzle over !

 

[Tigman]

That's my humble opinion , im no expert so don't slate me

 

[Kayos]

I used to put a bypass between boiler flow and the return so when the mid position valve closes (both ports) the pump can still pump ! And the cylinder coil return as close to the heating return as possible , where is the pump ? What type of boiler ?

Mid position valves dont close, they rest in hot water so either do hw, both or ch

An S plan requires a bypass

 

[Tigman]

I know , but I still put a bypass in !

 

[johnik]

No pump in pictures I can see ?

pic one, lurking just to the right of the valve

I think when heating and hot water are both calling for heat , the pumped water prefers the heating circuit because the cylinder return is 15mm and is restricting the flow so the heating takes priority when the heating is satisfied the water will go around the cylinder coil , that's why it works when it's hot water only , have you a room stat for heating ? , if you fire it up feel coil return see if it's cold , then turn off the room stat then feel the same coil return if it gets hot straight away , puzzle over !

thanks, i shall give that a try in the morgen.

 

[Cobbler]

I‘m thinking I ought to change the 3 port valve as it bangs, see Post 4, are they all the same dimensions & wire colours, or are they make specific. Also looking on the Screwfix website prices vary from about £60 to £100+ is there any advantage going for the dearer one? The valve I have at present is an ACL one.

 

[Kayos]

Don't buy a cheap one, you will regret it

 

[johnik]

I‘m thinking I ought to change the 3 port valve as it bangs, see Post 4, are they all the same dimensions & wire colours, or are they make specific. Also looking on the Screwfix website prices vary from about £60 to £100+ is there any advantage going for the dearer one? The valve I have at present is an ACL one.

all seem to be the same dimensions and wiring colours, the one i have is a Honeywell so not cheap, i hate plumbing as i always get leaks so just run it at speed 1 for the mo, come summer i may take a brave pill or have found a decent plumber by then.

 

[Cobbler]

Don't buy a cheap one, you will regret it

Thanks for that

 

[Cobbler]

all seem to be the same dimensions and wiring colours, the one i have is a Honeywell so not cheap, i hate plumbing as i always get leaks so just run it at speed 1 for the mo, come summer i may take a brave pill or have found a decent plumber by then.

I don’t mind changing it, it’s in the loft, so plenty of room. If the wiring colours are straight & it’s the same size, that’s good news. Thanks