is my boiler coil leaking or blocked

[muller]

I have a vokera boiler with a drayton mid way valve to choose either h/w or c/h or both. When valve is set to c/h everything works fine but when valve is set to h/w the vokera boiler cuts out after running for approx 3 minutes.
Is the coil blocked or has it got an air lock?
I had a plumber fit the new drayton mid way valve as the previous valve started leaking. Since the new valve has been fitted, all i hear now a trickling noise in the water cylinder and also in the bathroom radiator when the valve is set to h/w.

Ive been told the coil might be leaking or blocked. There is no water dis colour from the hot taps.

If its any help, the radiator in the bathroom used to get hot when h/w or c/h but now only gets hot with c/h.

I was informed by my plumber that it should get hot on both settings which is what it used to do

Any ideas or help will be greatly appreciated. My heating system is a sealed system.

 

[diamondgas]

:welcome:
Do you have plenty hot water? Not sure exacly what your issue is muller 🙂

 

[ManchesterGas]

Is there a vent on the top pipe on the side the cylinder? If there is, try and bleed it, if not, loosen the union a little until the air is out if there is any? Does this pipe and the one below get hot when set on hot water?

 

[muller]

I recently had my system flushed and a magnaclean fitted and also a new pump (grundfoss) and aav.
Ever since the new items have been fitted, my heating works fine but the hot water only heats up when the 3 way mid position valve is on hw & ch.

When the drayton 3way valve is on HW only, the boiler ignites, runs for approx 3 minutes then shuts off and no hot water. (this only happens on HW only) When the Drayton valve is on CH, every thing is fine. When the drayton valve is on CH and HW, my heating works down stairs but not upstairs and this also slowly heats the hot water. When the drayton valve is on HW, the flow to the coil in the cylinder is hot the but return is cold which tells me there is a problem with the coil but not being a plumber I cant say. I just want an idea of what might be wrong before I call another plumber. Hope this helps

 

[muller]

the flow pipe going into the cylinder gets very hot but the pipe returning stays cool but I hear water trickling noises from inside the cylinder. The bathroom rad does no longer get hot when on HW but does on CH. I dont see a vent screw, just a pipe which seems to be a vent pipe going into the header tank to fill the cylinder. My boiler is a sealed system but the water cylinder has a header tank and there is a breather pipe which slightly over hangs the header tank. Hope this helps

 

[diamondgas]

sounds to me like you have flow issues. With a new pump you'd expect it to move anY air locks. Is the actuator on the diverter on the right way around? Just a thought 🙂 Not even sure they can be fitted wrong TBH 🙂

How long ago was it flushed? May pay to get them back IMO

 

[muller]

I think I shall get the plumber back. It was all flushed about 2 months ago but since the new drayton 3 way valve was fitted its never been right. Im not 100% sure if the rads were balanced properly either. What confuses me is when drayton valve is set to hw and ch my water heats up, but when valve is on hw, the boiler heats up then cuts out. The flow to the cylinder coil is hot but the return is cold and the rad in the bathroom is cold too where as it used to get hot either hw or ch. It sounds like a flow problem to me or trapped air even but the only way i can see of removing air is loosening the main piping to the cylinder. But not being a plumber I think I shall get the plumbers back to sort it out. My worry is when winter finishes, I will have no hot water as it only heats up slowly when the ch is on.
Thanks for all advice on here

 

[diamondgas]

You've paid someone to resolve circulation issues by the sounds of it muller. A flush should overcome circulation issues or it hasn't worked IMO ... Good luck for the new year 🙂

 

[Gunner-rob62]

Is the pump running when HW only?

 

[muller]

Is the pump running when HW only?

yes the pump is running when HW only but the radiator in bathroom stays cold where it used to get hot on hw only. The only thing i can say is i can hear water trickling in the pipework when on HW, Ive checked the water colour from the taps and its clear. I have had all the system flushed and new pump plus AAV plus Drayton mid pos valve replaced. What confuses me is the bathroom rad should heat up when on HW but it stays cold but it heats up when on CH.

 

[Simon F]

Since the new valve has been fitted, all i hear now a trickling noise in the water cylinder and also in the bathroom radiator when the valve is set to h/w.
Ive been told the coil might be leaking or blocked.
My heating system is a sealed system.

are you loosing pressure in the system, if not then the coil is not leaking.
if the problem only started after the new valve was fitted, could be wired up wrong even possibly fitted back to front as well.

 

[muller]

are you loosing pressure in the system, if not then the coil is not leaking.
if the problem only started after the new valve was fitted, could be wired up wrong even possibly fitted back to front as well.

Hi its not loosing pressure at all. The radiators all work when the drayton valve is on CH but when valve is on HW the boiler ignites, heats up then cuts out which to me says a blockage of some kind. When the boiler is running the CH, the drayton valve switches over to CH and all the rads work, when both HW and CH are on, the drayton switches mid way to allow both but in this position not all the rads get hot. Its a plumbers job i think I just wish I could understand why its gone wrong

 

[tweakyboy]

Do you have a gate valve on the return pipe from the cylinder which would be used for balancing? Could be blocked up with crud!

 

[Simon F]

as its not long since the work was done, and its never been right, you need to get the plumber back

 

[muller]

Do you have a gate valve on the return pipe from the cylinder which would be used for balancing? Could be blocked up with crud!

I cant see a gate valve unless its fitted under the floor boards, just my luck if one is fitted under the flooring.

 

[muller]

I think the first job for my plumber in the new year is to sort out this mess. Thanks to all who have advised me on here

 

[vipey]

Hi i no i new to forums and i dont have loads of central heating exp but , surely the rad in the bathroom wouldnt even come on when it was switched over to h/w it would only come on when c/h was put on ?

 

[dancinplumba]

Hi i no i new to forums and i dont have loads of central heating exp but , surely the rad in the bathroom wouldnt even come on when it was switched over to h/w it would only come on when c/h was put on ?

sometime....... in the far far distant past the bathroom rad was connected to flow an return of dhw heating circuit so that bathroom was warm when you had hot water on.... seems good idea to me🙂

 

[vipey]

ahh oki 🙂 heat leak rad ?

 

[Simon F]

I was thinking about this, bathroom rad was said to get hot for both hw + ch if it was an older control with only HW or HW+CH linked to a 2 port valve ok that would be easy to configure. but it was said to be a mid position valve, how would the pipework need to be laid out for both to work, if its using check valves that might be the problem with the blockage?
or is Muller just describing reverse circulation, and been fobbed off and told its right?
what am I missing here?

 

[Ged Simpson]

This is a mysterious problem and I can think of only one explanation for all the symptoms. If the new mid-position valve has been completely incorrectly fitted to the wrong connections i.e. if the feed from the boiler has been connected to port 'A', feed to the HWC to port 'B' and the feed to the CH circuit to port 'AB', then that would explain the boiler cutting out when 'HW only' requested as it would be pumping against a closed valve. When 'CH only' requested the valve would move to cover the HW circuit outlet and permit flow to the CH circuit. When in the mid-position, both circuits would get feed, but if the return from the HW circuit has been teed into the return between the upstairs and downstairs return line, that would explain the upstairs not getting any flow in this situation. A rather unlikely scenario I must admit, but the only one that seems to fit the symptoms.

 

[jtsplumbing]

Hi I`ve had this problen in past as said check how valve is fitted ! if you look on valve you will find :

AB ---- this is supply from boiler

A ---- this is to central heating

B --- this is to hot water :confused5: