HELP Boiler Issue!

[Mujnu]

Hi guys,

I’ve recently had a new radiator system - 13 rads - along with a new boiler and Nest 3rd Gen thermostat installed. The boiler is a Worcester Bosch 8000 Greenstar Life Gr8300iw 35 C Ng (35Kw combi boiler). The TRV are all danfoss ras-c2 on normal rads and standard chrome valves on the vertical rads.

The Nest thermostat is in my hallway and is wired directly to the heat link which is then wired to the boiler, the thermostat is then connected wirelessly to work with the app.

The problem is quite a weird one so I’ll explain the best I can...

Lets assume the ambient temp is 17°, I then crank up my thermostat to 30° which then fires up the boiler and rads start getting hot - normal thermostat procedure.

My problem starts here, the radiators at times will get luke warm at best and stay at that temperature. I then need to switch the thermostat on and off a few times via the app the radiators will eventually start heating up to a point where I can’t touch them. Other times I’ll switch the heating on and radiators will start getting red hot as they should.

I don’t think the TRVs are switching the rads off as the rooms/hallways are not overly hot. And when the radiators want to work they stay hot for a very long time without cooling down.

The boiler also stays firing throughout from initial thermostat temp change until i turn it off. I’ve checked the heat link and when I turn the thermostat on it clicks and fires the boiler up and shuts it down when i switch it off.

The radiators have not been balanced and there is no air in the system as the rads get hot top to bottom and I have checked each radiator with a key to make sure. The system was cleaned out twice and the water was coming out clear so I assume it’s not a dirty system. When I have bled the radiators the water has a slight yellow tint to it.

I don’t understand what on earth is going on, is my boiler to blame or thermostat? Is it a balancing issue?

The current installers are very hard to get a hold of which is also causing me unnecessary stress as me and the wife like a toasty home.

Would appreciate any help

 

[Chuck]

If the radiators haven't been balanced that needs doing. The boiler pump setting needs to be checked as part of the process. This is all a required part of the commissioning process and needs to be done in a reasonably careful manner for the system to work well.

 

[Scott_D]

Might be that the boiler run at minimum for a while then gradually increases.
I’m not familiar with the 8000 but other boilers do this.

 

[Mujnu]

If the radiators haven't been balanced that needs doing. The boiler pump setting needs to be checked as part of the process. This is all a required part of the commissioning process and needs to be done in a reasonably careful manner for the system to work well.

I know the boiler fitters did the commissioning but from what I seen they didn’t adjust anything and said the boiler does the commissioning itself...

 

[Mujnu]

Might be that the boiler run at minimum for a while then gradually increases.
I’m not familiar with the 8000 but other boilers do this.

It’s weird because sometimes the boiler will fire up and then the radiators get red hot within 20 minutes and other times it just doesn’t want to do it :/

I’ve been told it could be due to the system not being balanced, the boiler could be short circulating so the return temperature at the boiler has almost been reached when the radiators haven’t heated up correctly.

i know nothing about boilers so trying to get a better understanding

 

[ShaunCorbs]

Tbh get the fitters back could be a few things the nest in optimal start / load start/ weather comp

 

[Scott_D]

Any pictures of the boiler and pipework underneath?
Could be a dodgy bypass.

 

[Mujnu]

Any pictures of the boiler and pipework underneath?
Could be a dodgy bypass.