Heating zones problem (radiators not coming on)

[MrDarkGray]

Hello everyone,

I’m experiencing some problems with my dual-zone central heating. The system has a boiler in the downstairs kitchen and a hot water tank with an expansion tank on top on the first floor. The ground floor is controlled via a thermostat down there, and the first and second floors via a thermostat on the first floor. I have no issues with taps or shower hot water.

When I change the thermostats either on the ground or first floor, I can see the respective valves by the hot water tank shut and open as expected. However, I have been having issues with the hot water not heating the first and second floor radiators.

I started by bleeding all the radiators, and all were fine, but one at the very top of the house needed a lot of blading. I then refilled the boiler pressure.
I then checked the pressure of the expansion vessel and found that it was very low. So I topped it up to 3 bars (as found by searching online as I couldn’t find any lanes on the vessel itself) and again topped up the boiler pressure. When I inspected the system, I found that the tundish had a small leak, so I replaced the TPRF. And the leak has now gone. I can’t detect any more issues; however, I still have no radiator heating on the upper two floors. Can anyone advise any solutions or things to check? (The gauge picture is the only gauge near the hot water tank and have no idea what part of the system it measures)

 

[ericmark]

I take it the pump is running?

 

[MrDarkGray]

There is no pump on this system. Just the water pressure.

 

[ericmark]

I will guess pump inside the boiler casing.

 

[Johntheo5]

That pressure gauge (looks like it) measures the mains water pressure after the PRV (pressure reducing valve) and is the supply to the unvented HW cylinder, if so, has nothing to do with your problem.
If there is a pressure gauge on the front of the boiler, check its reading, should be 0.7bar/1.0bar with a cold system and boiler off. If no pressure gauge, you have a open vented boiler with a feed and expansion cistern (a small tank) in the attic, check that this is ~ 1/3rd full of water, go back to bed.

 

[MrDarkGray]

Thank you for your reply John. The boiler does have a front gauge and it does show the correct pressure. All the water tanks are on the first floor as in the picture with nothing in the attic.

 

[Johntheo5]

What make/model Boiler do you have?

 

[MrDarkGray]

A potterton gold system 24he a