Radiators Don't Heat Up Enough

[Sanjit]

I have a Charnwood Country 15B stove. I’m having a problem with the radiators not warming up enough.

There’s a thermostat on the outgoing pipe which is set to 85 degrees, and the thermostat on the incoming pipe is currently set to 40 degrees. The thermostat on the incoming pipe is what triggers the pump to circulate the water round the radiators.
I spoke to Charnwood and they said the incoming thermostat should be set to at 60 degrees. The problem I have is that it never gets to 60 degrees.

There are 10 radiators in the system, currently 3 of them are turned off. The pump is currently set to low, I’ve tried it at medium and high and it doesn’t seem to make any difference.

Any ideas what the problem may be?

 

[snowhead]

Is this a brand new system or ons in a house you have just purchased?
If new, who designed,installed and commissioned it?
How does the total radiator load compare to the boiler spec of 13kw?

Is there also a Hot water cylinder as part of the system?

 

[Sanjit]

We're renting a house and from what I know it was installed a few years ago. There is a hot water cylinder as part of the system.

 

[SimonG]

As above, what else is linked and is it done properly?

 

[Sanjit]

Nothing else is linked and from what I know and can see it seems to have been done correctly

 

[Brambles]

I would raise the issue with your Landlord and suggest that the stove is serviced. Arrange to be there when the service person is present and get them to explain the full system operation to you and the routine cleaning operations - particularly the throat plate adjustment and and air sweep to keep the glass clean. Also get their view on the “quality of the system as installed”.

The symptoms you describe could be that the throat plate is not correctly positioned or is distorted or the system is sludged. Be aware that an excessive hot water demand will impact output on the pumped heating system. However, in my experience, a lot of these systems are not designed and installed correctly - so they never work as intended by Charnwood.

You stove needs a gravity hot water system, a gravity 1kw (ish) heating loop and a balanced pumped central heating system to work correctly.

A low boiler return temperature can be accommodated, but in a correctly designed and clean system is indicative of too low a flow rate.

The Charnwood room heater will only work properly and to specification is there is a full correctly configured hot water / central heating load. If the water load is reduced so too will the room stove output.

Sorry, if this is not what you want to hear.

If you want to troubleshoot yourself first:

Ensure that the throat plate is clean, not distorted and correctly positioned.

That the system is clean and not sludged.

Switch off the central heating pumped loop.

Operate the DHW system and get it up to temperature. Don’t draw off any hot water.

Check the gravity heating system - normally one radiator - and ensure that it is functioning correctly - it should get very hot.

Close off the radiator valves on the pumped heating system. Switch on the pumped heating system and bring in the radiators one at a time - a quarter turn is normally sufficient - bleed the system as required. Once all the radiators are warm try to balance the pumped heating system. Unless the radiator load is oversized for the system, after balancing they should all be hot to the touch. If not try closing off one or two radiators and see what impact that ha

At all times during set up, ensure that the stove is on full load and has sufficient fuel.

If nothing else, the above will start to give you a better understanding of how the system works.

 

[Sanjit]

Thank you Brambles for one of the most comprehensive answers I've ever seen.

I'll try all those things out. We noticed yesterday that when the radiators get warm it's only the top, the bottom remains cold suggesting sludge in the system. I'll speak to our landlord as the system may need power flushing.

We don't use the system to heat the water as it's not effective, we tend to use the immersion heater. We only use the system to heat the house.

I'll try only keeping one radiator on and will check the throat plate. Thanks again.

 

[snowhead]

What fuel are you using?
Although it doesn't say so in the instructions for the Charnwood Country 15B boiler, outputs are quite often derated when only using logs.

 

[centralheatking]

Get some seasoned hard wood this has a higher calorific value than soft wood, and what sort of soft wood are you using it makes a difference. eg Poplar will show a flame but no heat at all.
centralheatking

 

[Sanjit]

We're burning mainly olive and lemon wood (I live in Cyprus).
[automerge]1578068715[/automerge]
So I turned off all the radiator apart from one and the incoming temperature rose to over 60 degrees and the radiator was perfect. Started to open a few more radiators and the temperature dropped to 45 degrees (still hotter than before). At the moment I have 4 radiators out of 10 open, and we're around the 50 degree mark and the radiators are nice and warm. Could it be a pump issue? It's on the medium setting.

 

[centralheatking]

We're burning mainly olive and lemon wood (I live in Cyprus).
[automerge]1578068715[/automerge]
So I turned off all the radiator apart from one and the incoming temperature rose to over 60 degrees and the radiator was perfect. Started to open a few more radiators and the temperature dropped to 45 degrees (still hotter than before). At the moment I have 4 radiators out of 10 open, and we're around the 50 degree mark and the radiators are nice and warm. Could it be a pump issue? It's on the medium setting.

Classic underpower heat input but you are being quite forensic well done. Now I would make sure all the downstairs radiators are as best as you can get....heat rises ..especially if you leave bedroom doors open then the upstairs will get heat. Try putting the pump over to 3 but its really a heat input issue and
you might get 'pump over' not good makes things worse. However if it is a bit sludged up a higher setting on the pump might clear it out ...its a bit like heart surgery for heating systems.
regards Centralheatking