potterton combi problem

[bradchop]

Hi guys, i hope someone can help me out. I went to a property today to do a powerflush and change the boiler pump as the heating system wasnt getting hot downstairs at all. it was getting warm upstairs just. the outcome is the system is alot better but..it still is in need of more heat.. the boiler seems to fire up for about 15 seconds and then cuts out, 2 mins later it does it again. i realise boilers 'cycle' but this is way too short to heat an 8 rad sytem. before i changed the pump it fired up for way longer than that.


does anyone have any ideas?? many thanks :freak:


boiler is a potterton combi 80 gc 47 393 03.
flow and return pipes head upstairs first.
8 rad system.
the system has been properly flushed.
new 6 metre head pump cp61.

 

[bradchop]

forgot to say that there is no external controls or room stats. thanks guys

 

[diamondgas]

1st thought would be a dodgy sensor? How hot is the flow getting leaving the boiler before it shuts down?

2nd thought would be a dodgy diverter? But there's some observations need to be made before you jump to that conclusion

3rd thought could have something to do with the flue/fan ... not going there in an open forum

Once again I'd like to feel the flow and return pipes at the boiler to see what was going on!

 

[bradchop]

1st thought would be a dodgy sensor? How hot is the flow getting leaving the boiler before it shuts down?

2nd thought would be a dodgy diverter? But there's some observations need to be made before you jump to that conclusion

3rd thought could have something to do with the flue/fan ... not going there in an open forum

Once again I'd like to feel the flow and return pipes at the boiler to see what was going on!

Hi pal, thanks for such a quick reply.

the flow pipe is steaming hot and the return is luke warm. i have heard that replacing the wax capsule on the diverter might help??

the flue and fan seem fine, definately no restrictions and its running very strong i believe.

 

[diamondgas]

I was thinking of a completely different boiler!! lol

1st thing to check for is a dripping hot tap!!! Honestly! It can make all the difference between heating and no heating! Then you look at replacing the wax capsule IMHO

 

[bradchop]

that was the first thing i looked for was a dripping hot tap but to no avail unfortunately. i ve heard that the wax capsule restricts the ch flow therefore making it impossible to heat a decent sytem??
i hope this helps it otherwise im gona look a complete twonk :sad_smile:

 

[diamondgas]

that was the first thing i looked for was a dripping hot tap but to no avail unfortunately. i ve heard that the wax capsule restricts the ch flow therefore making it impossible to heat a decent sytem??
i hope this helps it otherwise im gona look a complete twonk :sad_smile:

Do they have a filter fitted?

The capsule expands when hot and opens the valve! I've seen them in some states when they've gone!!! I'm also a touchy feely type of guy I like to feel how hot the integral return to the boiler is if you have access? It can indicate where the water is circulating

 

[zeebeedee]

Flow pipe under the boiler or inside? Under I'd be looking at the pump or sludge. Inside wax diverter.

 

[bradchop]

Do they have a filter fitted?

The capsule expands when hot and opens the valve! I've seen them in some states when they've gone!!! I'm also a touchy feely type of guy I like to feel how hot the integral return to the boiler is if you have access? It can indicate where the water is circulating

no filter fitted as far as i can see pal.
the internal pipes are hot as far as i can tell. integral return is cold.
im going to try the wax capsule and cross me fingers for a happy outcome :24:.

i hope im not missing anything haha!!
.

 

[bradchop]

Flow pipe under the boiler or inside? Under I'd be looking at the pump or sludge. Inside wax diverter.

flow and return pipe exit under the boiler, tail off right and then go straight up to the floor above. flow is red hot, return is cold for ages then gets luke warm. changed pump and did thorough power flush, thanks for your reply

 

[diamondgas]

no filter fitted as far as i can see pal.
the internal pipes are hot as far as i can tell. integral return is cold.
im going to try the wax capsule and cross me fingers for a happy outcome :24:.

i hope im not missing anything haha!!
.

If the integral return is cold then it indicates poor circulation .... not bi-passing the heating circuit and wizzing through the plate hex! ...... Worth a second check! I'd personally like to feel a red hot integral return to verify the diverter bi-passing the heating circuit

 

[REDSAW]

when you replaced the pump did you undo the bleed cap?

 

[bradchop]

when you replaced the pump did you undo the bleed cap?

bleedcap? there was a black plastic hex looking nut on the pump (cp61 pump) but i didnt touch it. i did get all the air out though thru the auto air vent at the top of the boiler. would the bleedcap make that much difference? have you come across the black hex nut before? ta

 

[bradchop]

If the integral return is cold then it indicates poor circulation .... not bi-passing the heating circuit and wizzing through the plate hex! ...... Worth a second check! I'd personally like to feel a red hot integral return to verify the diverter bi-passing the heating circuit

ok i will check the internal pipework first, what i did notice though is that it takes ages for the flow pipe to get hot initially, like its fighting to get up the pipe, when it does though its impossible to hold the pipe for long

 

[buckley plumb]

did you power flush from a radiator and through the boiler you could have sludged up the boiler filter.i would be tempted to drain and cut flow and rtn above boiler (you said they rise up) and flush mains water or powerflusher to the flow and rtn pipes and check you have a circuit around the rads that way you have prooved the rad circuit.

 

[diamondgas]

ok i will check the internal pipework first, what i did notice though is that it takes ages for the flow pipe to get hot initially, like its fighting to get up the pipe, when it does though its impossible to hold the pipe for long

That's the wax capsule! The boiler has to maintain a 'hot' capsule for the heating to work! You tend to get the flow mad hot initially then is should cool down as the heating circuit opens up Strange design to be honest, nicked from Vaillant If I'm not mistaken... lol

 

[bradchop]

did you power flush from a radiator and through the boiler you could have sludged up the boiler filter.i would be tempted to drain and cut flow and rtn above boiler (you said they rise up) and flush mains water or powerflusher to the flow and rtn pipes and check you have a circuit around the rads that way you have prooved the rad circuit.

hi pal, yes i did flush from a nearby rad. i also shut off all the rads and did a circuit of the boiler just to mak sure it was clear. sounded like it was gushing thru ok?

 

[bradchop]

That's the wax capsule! The boiler has to maintain a 'hot' capsule for the heating to work! You tend to get the flow mad hot initially then is should cool down as the heating circuit opens up Strange design to be honest, nicked from Vaillant If I'm not mistaken... lol

thanks pal, i hope your right. ive heard they are quite easy to fit also. cant wait for a return visit :freak:

 

[buckley plumb]

what is this wax capsule out of intrest . anyone got a link to the manual for this boiler

 

[diamondgas]

what is this wax capsule out of intrest . anyone got a link to the manual for this boiler

It's a mechanism incorporated in the diverter valve to open or close it depending on hot water demand! The fluid inside the capsule expands when hot and contracts when cold. the capsule is enveloped in the cold water mains inlet! Turn a tap on and it contracts ... tap off allows the hot water flow in the boiler to heat the capsule and expand, opening the diverter!! Strangest of concepts but was adopted for a period of time

 

[buckley plumb]

It's a mechanism incorporated in the diverter valve to open or close it depending on hot water demand! The fluid inside the capsule expands when hot and contracts when cold. the capsule is enveloped in the cold water mains inlet! Turn a tap on and it contracts ... tap off allows the hot water flow in the boiler to heat the capsule and expand, opening the diverter!! Strangest of concepts but was adopted for a period of time

thanks not seen one of these yet

 

[desrob]

out of interest does this boiler have an integrel by pass,if not has the system

 

[bradchop]

no integral bypass. there was a makeshift one near the boiler but the heat just came out and went back through again. totally losing all heat power to the main system so i shut it off and have now created a bypass with a 2 lockshield rad

 

[bradchop]

update!!! it was the wax capsule after all!!! i am so pleased it worked. many thanks to everyone that helped. that made my day!! :smilewinkgrin: it also made the customers day as they had a warm crisp house after about 5 minutes. amazing how much difference something that small can make!!

 

[bradchop]

It's a mechanism incorporated in the diverter valve to open or close it depending on hot water demand! The fluid inside the capsule expands when hot and contracts when cold. the capsule is enveloped in the cold water mains inlet! Turn a tap on and it contracts ... tap off allows the hot water flow in the boiler to heat the capsule and expand, opening the diverter!! Strangest of concepts but was adopted for a period of time

thanks pal..it was the wax capsule - i would never of even thought about that..the guys at the technical didnt even know!! top man!!