Potterton 24 Combi Boiler possible high pressure

[jonahjones]

Hi,


I have a Potterton 24 he eco boiler and have noticed the pressure getting quite high when the heating is on.


When cold the pressure is set 1 bar. When the heating is on it rises to around 2.5 - 3 bar.

When the hot water is on it goes to 1.5 bar.


It is quite possible it has always done this.


My question is I have just had the boiler serviced?


I have spoken to the guy who serviced it and he said he noticed the pressure a bit below 1 so he topped it up and the reason the pressure was below 1 might be because the expansion tank isn't working and water is being released from the system.


Is the expansion tank something that they should check?


Are there any checks I can do?


Thanks
Paul

 

[jonahjones]

Hi again.

Did a proper test tonight. Ran the boiler calling for heat and watched the pressure rise from 3/4 bar to 3.5 bar.

At this point the copper pipe in the garden let out some water and the boiler then stopped heating shortly afterwards.

It has probably been doing this a while but I haven't noticed as our house warms up so well and quickly.

Questions are.

Should the guy who serviced it last week have noticed this?
Is there an easy way to tell if the pipe to the expansion vessel is blocked?
If it is the expansion vessel does that mean its the diaphragm or the vessel itself?

How much could this cost me?

Sorry for all of the questions.

Thanks
Paul

 

[glenntaf]

Sounds to me like typical symptoms of a faulty expansion vessel. A burst / undercharged vessel means that the excess pressure that is created when the heating is on has nowhere to go and so 'blows off' outside through the pressure relief valve. However accessing the vessel usually requires removing the boiler casing and so should be carried out by a registered gas installer. Although a sometimes cheaper / easier fix can be achieved by fitting a second expansion vessel to the return central heating pipe work to the boiler (providing you have the room)

 

[glenntaf]

Also a faulty expansion vessel is not usually something that would be checked on a service unless your engineer was aware of a fault when he started servicing it.

 

[solutions]

Also a faulty expansion vessel is not usually something that would be checked on a service unless your engineer was aware of a fault when he started servicing it.

It is required to be checked by some manufacturers. I check precharge as part of a service on any boiler or system that has one.

 

[jonahjones]

Thanks for your replies.

I checked the vessel by squeezing the value and it let out air rather than water. This is a good sign so I have read.

I didn't check the pressure as I haven't got a pump at the mo so will check tonight. Basically I didn't want to check the pressure and at the same time let loads out with nothing to put it back.

Should the pressure be 1 bar for this model.

If it needs represurising I was going to bleed a rad until boiler pressure is 0. Then make vessel 1 bar pressure. Then top the boiler back up.

Are there any other steps to take and does the fact that the vessel released air mean the vessel is fine. I am thinking it might just need repressurising or the pipe to it is blocked.

Last question. Does the boiler have to come off of the wall to replace these vessels?

Thanks

 

[anz]

It is required to be checked by some manufacturers. I check precharge as part of a service on any boiler or system that has one.

On some as soon as you touch the valve, they start leaking air.

 

[solutions]

To replace it or repressurise it if i recall corectly you will need to take the case off to access the connections and valve so it is work that will need to be undertaken by a gas safe registered engineer. The manufacturers instructions normally state the precharge for the vessel or there is likely a label on the vessel itself with the details. 0.8 - 1 bar is fairly typical. I know several engineers on the forum renew the schrader valve if it needs repressurising as if it has not pinholed it must have lost charge through the valve.

 

[jtsplumbing]

Rather than mess around with something you don't fully understand, why not call the engineer back and get him to check it,you could have other problem's, how meny radiators on system, exp tank could be undersized for system.

 

[jonahjones]

Thanks.

I will get an engineer in but access to the value on the exp vessel is very easy and if it just a case of reducing the system to 0 pressure and ensuring the vessel has 1 bar then it could be a simple fix rather than spending loads on someone to do it for me.

Anything above this in terms of difficulty I accept is beyond me and I would get someone in to do it.

 

[jonahjones]

Hi guys,

Am ready to call the engineer back.

I bled a rad and got the pressure down to zero.

Checked the expansion vessel and it had no pressure.

As I was adding pressure via a pump to the vessel I noticed the boiler pressure go up as well?

What does this mean?

Thanks

 

[REDSAW]

your adding pressure to the system!.

there is a correct procedure to doing this, but correct me if i am wrong..have you taken the case front off the boiler to access it?
btw, a service is not a repair that comes as extra!

 

[jonahjones]

I think I worked out where I was going wrong.

The pressure goes up in the system because the vessel has water in it. I carried on adding a bit at a time and then bled the rad until the system pressure went to 0. I repeated this until adding air to the vessel no longer increased the system pressure meaning the vessel was empty.

I then put 0.8 bar into the vessel and 1 bar in to the system.

With the heating on full the pressure remained at 1 1/4 bar.

I have read that the vessel needs 0.8 - 1 bar on this boiler? Could someone confirm this for me?

Also to access the vessel the front didn't have to come off. Just a metal plate across the top let's you reach in straight to the value.

This may not be a permanent solution but worth seeing if the vessel had lost pressure over time. 8 years.

I know a service doesn't include repairs but was surprised a service doesn't include checking the vessel.

Thanks for being patient with me.

 

[solutions]

I think I worked out where I was going wrong.

The pressure goes up in the system because the vessel has water in it. I carried on adding a bit at a time and then bled the rad until the system pressure went to 0. I repeated this until adding air to the vessel no longer increased the system pressure meaning the vessel was empty.

I then put 0.8 bar into the vessel and 1 bar in to the system.

With the heating on full the pressure remained at 1 1/4 bar.

I have read that the vessel needs 0.8 - 1 bar on this boiler? Could someone confirm this for me?

Also to access the vessel the front didn't have to come off. Just a metal plate across the top let's you reach in straight to the value.

This may not be a permanent solution but worth seeing if the vessel had lost pressure over time. 8 years.

I know a service doesn't include repairs but was surprised a service doesn't include checking the vessel.

Thanks for being patient with me.

Service should and does include checking the vessel.