Radiators not heating evenly

puddy

We moved in this house 18 months ago and have not had a problem with the heating. 2 storeys and a combi boiler

so recently we noticed that the radiators upstairs are only slightly warm at the bottom and cold at the top, apart from the one in our bedroom which is hot all the way to the top but not on the left hand side, ! only on the right hand side.

So, OH tried to bleed the radiators and a little bit of air came out of them but no water moved to the top (assumed by the fact that no water came out)

I had also noticed that in the last month or so whenever the heating was on or the hot tap used the boiler made some clanging noises.

Any ideas?

macman

Sounds like not enough water in the circuit then, Did you top it up via the filling loop under the combi after you bled the rads?
What pressure do you have on the gauge?
If rad areas other than the tops are not warm, then it sounds like you have sludge or an airlock in the sytem, but sort the pressure out first and retest it.

ariba10

Try turning off the hottest radiators while the system is working and see what happens.

1984ReturnsForReal_2

Have you got thermostatic radiator valves on the ones upstairs that you are having problems with?

And if you have are they on all the radiators in the house?

puddy

sorry for the delay and thanks everyone

we have a sime boiler and OH says that the pressure thing says 0.

we have a leak under the kitchen sink from some sort of pipe, he says we cant afford a plumber so have been catching the water in a bowl for about a year. now i wonder if this is connected to the heating problem

yes some of the radiators upstairs have thermostats on them , quite new looking, they are all on 5 which is the max, the others just have a turn thing with - or + on it, old fashioned looking on a white plastic knob

the manual for the boiler says that a 'competent person' should look at it, so OH says he cant but wont pay for anyone else to do it...

macman

Is it a SIME combi boiler (no hot water tank)? Model?
What is the leaking pipe under the kitchen sink? Is it related to the boiler or CH circuit? It seems unlikely in that location.
If the pressure on the gauge is zero then you need to repressurise the system by topping it up from the filling loop under the boiler, this is a job you can do yourself quite easily, just open the valve on the loop until you have a pressure of about 1.5, and then close it. Then try to fire the boiler again.
What will your OH pay for?

puddy

thank you, we will try that.

puddy

thanks everyone, we raised the pressure as advised and its done the trick although when the heating goes on or the hot tap is used, the pressure goes up to over 2 is that right?

keystone

puddy wrote: »

thanks everyone, we raised the pressure as advised and its done the trick although when the heating goes on or the hot tap is used, the pressure goes up to over 2 is that right?

You have a sealed system. When you heat water it expands. If the system is sealed then that expansion manifests itself as a pressure increase. So yes it is quite normal for the pressure to rise when you have the heating on. As long as it remains below 2.5 / 3 bar you'll be fine. If it goes up to that level the Pressure Relief Valve will operate to dump the excess pressure. Thats for safety.

Your DHW is a separate circuit entirely from the CH and fed by mains cold water and uses a separate heat exchanger in the boiler. So the pressure should not rise when you run a hot tap. As its likely that the two heat exchangers will be adjacent to one another then it's is possible that you will get a small pressure rise just by heat transfer.

Are you running the hot tap with the CH off and cold or with the CH on and hot? What happens if you run the hot tap with the CH off and cold?

Cheers

puddy

i think the heating has been on when i noticed the hot tap affecting the pressure, will try it tomorrow with the heating off and cold and see what happens. its nice and toasty and im nice and comfy now so feeling a bit lazy!