Is there a plumber in da hoose ?

[johnik]

Greetings all, a question if i may.
during the summer my indirect hot water tank sprung a leak, a plumber replaced said tank and 3 port valve, life was good.
just before christmas i noticed that if i switched from just HW to CH/HW, the water from the tap was just warm so i have to switch back to HW to do the washing up, also the water is just about warm by morning where it used to be hot until the timer came on again (16-00), a further thing is, when it fires up initally, there is a loud bang and the tank shakes but only if it is set to HW/CH, if i select HW for 1/2 hour then change over to HW/CH, all is quiet.
the plumber who did the job is not answering his phone now so cant get him back, i am thinking 3 port valve is duff (Honeywell).
any ideas please ?

 

[dobbslc]

Where's the bang coming from? Boiler, valve, cylinder? Did it work properly just after the cylinder and valve were changed? It does sound like a duff valve but can't see why that would make a loud bang as they move very slowly. Could be an air lock.

 

[Kayos]

Sounds like it is the valve

 

[Cobbler]

The 3 port valve on our system can make a loud bang when it changes from heating to hot water, I think the pumped water pushes it across under certain conditions. You can see the valve twist the pipes slightly at it changes due to the torque on it. The system has been in 20 years & it did it at the start, I changed the valve & it still did it. Then it stopped for a long while, but I’ve changed the pump & it’s doing it again. I think the new pump has a bit more go & forces it across. I spoke to the manufacturer some years ago, but they couldn’t understand it, or didn’t want to.

 

[mike os]

my first thought is its wired wrong, and an airlock,

only way a 3 port could bang is if the springs broke

 

[gaz1]

loud bang is the sticking valve giving under pressure of the pump

its also a warning to stop using it if it dosnt give you have problems

 

[johnik]

thanks for the replies peeps, i cant see where the bang is coming from, sounds like the cylinder itself.
it has been working fine since it was fitted so not a wiring problem, i have bled the rads and the valve thingy on the cylinder, no air to be seen.
looks like ill go and get a new valve then, thanks again peeps.

 

[Mikes]

Check that he has put the valve in the correct way. Depending upon the controller, should be so that the cylinder is normally open to the pump / boiler and motors to heating when called for. Valve body will be marked A, B and AB. Port A should be to the radiators, Port B to the hot water cylinder and port AB should be from the boiler / pump.

 

[brightspark]

is the valve the one with the metal case and a slide lever on the side . operate it manualy its spring return if water and heating are turned off and should run back smoothly you can check the small motor inside if you remove one screw and turn it to get it out put ther heating on and you will see the little brass cog run if its ok if it dont there ony 14 quid from screwfix and easy to replace .check make sure your circulating pump is running properly as well if it has 3 settings on it change the speed and see if theres a diffence in flow.you can hear it run

 

[johnik]

as above, it has been working fine since summer, obviously i just put the heating on a few weeks ago but was ok till just before christmas.
tis the metal cased one with lever, that all seems to work, i can hear the motor whiring when turning it off, seems strange that it only happens when on HW/CH and the first time i turn it on, it dont happen when HW only is selected.
pump is nice and quiet and the sound changes when i change speed
i have ordered a new valve, i tried changing the top part before and it ended in tears so for the sake of £50

 

[Tigman]

Send some pictures of the pipe layout in the airing cupboard ??

 

[Tigman]

Can't see image johnik ?

 

[johnik]

 

[johnik]

 

[johnik]

 

[johnik]

Can't see image johnik ?

bit early in the day for me...thats my excuse anyway

 

[Mikes]

Neat enough pipework but that hot water flow of the cylinder is so wrong. Your plumber should have cut the tee out of the vertical flow / vent pipe and installed a new one higher up. Think he cut a corner to save himself time.

 

[gaz1]

its an a/b valve bottom feed

plumbers done a poor job really

middle pic well that part can air lock badly top of the tank

last pic tee fitting should be down and drain point downwards or at an angle the return pipe sould be direct not restricted strange why it goes up when infact it should be going back down

also should have been straight out of the fitting not in the middle of the tee basically its a flow ratio faster the water returns the quicker the tank heats up

the jack up tank level well i understand its to spread the weight but being that small its kinda a little useless really

 

[johnik]

its an a/b valve bottom feed

plumbers done a poor job really

middle pic well that part can air lock badly top of the tank

last pic tee fitting should be down and drain point downwards or at an angle the return pipe sould be direct not restricted strange why it goes up when infact it should be going back down

also should have been straight out of the fitting not in the middle of the tee basically its a flow ratio faster the water returns the quicker the tank heats up

the jack up tank level well i understand its to spread the weight but being that small its kinda a little useless really

thanks, you have really made my day , i try to avoid anything plumbing related as i always get leaks so let the friend of a friend who has his own plumbing company do it.
do you think it is the 3 port causing the lack of hot water and bang when CH is turned on ?, i have ordered a new valve but can always send it back if that is not the case .

 

[gaz1]

only way to truly find out is get someone to turn it on in morning when your at side of it

the only other way and its not what your quoting is a knocking sound and thats pipe vibration

for valve it can be over ridden by taking motor off and half porting it that will feed hot and central heating side of it

all depends on when the bang is porting it in morning after central heating run all night or when porting to the central heating side of it either way if that valve is sticking it will bang one side or the other