Sime Friendly - Fluctuating Pressure Guage

Hi,

Apologies in advance for my lack of technical terminology, I'm no plumber.

I've got an 'issue' with my Sime Friendly boiler. The hot water is fine and the heating is fine, but....

Heating off: Pressure guage reads 1.5 bar.
Heating on: Pressure rises until the reading is maxed out - it hits the pressure needle limiter - This is probably around 5 or 6 bar. I tend to switch the heating off again at this point!!

I've been told that it could be lack of pressure in another part of the boiler causing the reading to fluctuate and that I should try and find a schrader valve that a pump can connect to (like a bike pump). I've found the valve and connected a pump but the reading was 0 bar. I've since pumped this up to around 1 bar but the guage still fluctuates when the heating is on.

The valve is connected to a large red 'tank' at the back of the boiler which is accessed from above.

Question 1: Does anyone know how much pressure I should pump into this tank?

Question 2: Does anyone know of a website where I may be able to find this information - I can't seem to find a site for Sime?

Question 3: Is it safe to leave the heating on with the pressure reading as it is or would I be better off leaving it off? It's possible that it's always done this and that I simply haven't noticed it before - I just happened to glance at the pressure guage one day last week.

Many thanks in advance,
Matt.

mwatkins said:

Hi,

Apologies in advance for my lack of technical terminology, I'm no plumber.

I've got an 'issue' with my Sime Friendly boiler. The hot water is fine and the heating is fine, but....

Heating off: Pressure guage reads 1.5 bar.
Heating on: Pressure rises until the reading is maxed out - it hits the pressure needle limiter - This is probably around 5 or 6 bar. I tend to switch the heating off again at this point!!

I've been told that it could be lack of pressure in another part of the boiler causing the reading to fluctuate and that I should try and find a schrader valve that a pump can connect to (like a bike pump). I've found the valve and connected a pump but the reading was 0 bar. I've since pumped this up to around 1 bar but the guage still fluctuates when the heating is on.

The valve is connected to a large red 'tank' at the back of the boiler which is accessed from above.

Question 1: Does anyone know how much pressure I should pump into this tank?

Question 2: Does anyone know of a website where I may be able to find this information - I can't seem to find a site for Sime?

Question 3: Is it safe to leave the heating on with the pressure reading as it is or would I be better off leaving it off? It's possible that it's always done this and that I simply haven't noticed it before - I just happened to glance at the pressure guage one day last week.


Matt.

Click to expand...

the red tank as you call it is a expansion vessel inside is a diaphram air on one side water on the other when htg is on the water xpands and pushes agaist the diaphram if it is not charged properley this cannot take place so the htg water press will go up untill it is blown out from the prv. just pump up at the screader valve untill it is pushing back at u through the pump this should cure the prob.

Try this it may help, when the pressure is high on the gauge after you have had your heating on for a while let the pressure out of the shrader valve, dont go mad just let it out slowly, the purpose for this is to see if you have any condensation water in the vessel there could be as much as a few pints, as the pressure is high it should completely empty the vessel of water if there is any water obviously have some cloths or plastic sheets to protect the circuitry and isolate the boiler from the supply (electricity) before you try it may be just worth trying then if you can when it is all cooled down and the pressure is right down re inflate the expansion vessel to between 3/4 and 1 bar there are set proceedures for this but just do it the best you can. It may help especially if there is a considerable amount of water in the vessel.

Regards Clive

I should have said firstly it is not safe to let the system pressure get so high. There should be a pressure reducing valve (PRV) which should blown off at 3 bar reducing system pressure. Hopefully there is a copper pipe outside which doesn't go any where just stops has an open end, hopefully pointed at the floor, or at a gully or turned back into the wall. If you trace this back it should be connected to the prv everyones going to hate me for saying this but if the pipework is connected to outside and providing it is not pointed at the childrens play area give the valve a twist or pull the lever if the valve dont work then you need to seriously get it looked at, In the mean time try not to let it get so high you don't need the heating anywayjust yet.

Regards Clive

I understand that the instructions are in the FAQ section of this site.

To do it properly the system must be open when its pumped to 0.6 times the final pressure.

Tony