Boiler pressure increasing

TELLIT01

As it's a rented property definitely get onto the landlord. The pressures you report will find any weakness in pipes, radiators and joints pretty quickly. The last thing you or the landlord need is water at around 70 centigrade spraying across a room.

bris

as already said it should never reach 5 bar as the PRV should open and keep it under 3 bar so that needs addressed.


It could very well be a split heat exchanger which is leaking mains water into the heating side.

keith969

Something is severely wrong - everen 3 bar is too high. I'd get a plumber in asap.

chickendipperbabe

Does the pressure only increase when you run the central heating?

If so it could just be your expansion tank/vessel needs pumped up, you could do it with a bicycle pump at a push.

neilmcl

rwmorris wrote: »

I don't think it's a filling 'loop' it seems to just be direct water pipes going into it with a valve at the top just before it hits the boiler.

It's a Vaillant ecotec plus 831.

Have a watch of this and see if the filling loop valves are open - https://www.youtube.com/watch?v=Pv-SMJQO6XE

jaizan

1 The pressure relief valve should normally prevent the pressure from rising above 3.0 bar.

This is very basic plumbing and you or your plumber should check it releases water at approx 3.0 bar.


These are easily replaced. I did mine in about 30 minutes in the summer (due to leaking).


2 There should be an expansion vessel in the system because water expands as it gets hot. This is usually in the boiler. Mine is at the back, with a schrader valve. This should be checked.

If it has failed, you can either replace it, or plumb another one in the system.

You could try repressurizing it, by setting it to ~1 bar with the water pressure at zero. Then add water so it's approx 1.5 bar when cold.

My system has 2 expansion tanks and I did an excel spreadsheet to calculate "optimum" pressure settings. If you have too much water and not enough air in the expansion vessel, the pressure rise will be much more. I had almost 1.5 bar increase in pressure originally, but after setting it up properly, I got less than 0.5 bar increase in pressure.

Incidentally, as your plumber appears to have not checked the pressure relief valve, he has failed on the most basic task, so I suggest a better plumber is employed next time.

jaizan

Incidentally, this is good reading.


http://www.freeheatingadvice.com/articles/boiler-pressure/

wideboy09

Damaged heat exchanger most likely, if damaged the mains pressure cold can mix with the heating system water which should be totally separate.

Also as stated before your prv shouldn’t let the central heating pressure get that high without discharging

loyalstokie

naf123 wrote: »

I'm no plumber but it does look like the filling loop is valve is faulty . Did plumber replace it ?

I agree.



As you are renting I assume you don't want to attempt a repair yourself.

rwmorris wrote: »

Overnight it was left as is, nothing running, still increased to 3 by this morning.

You could try turning the mains off over night to see if it still happens.

We had a similar problem and disconnecting the filling loop pipe the putting a isolator valve cap solved the problem.