Central Heating

[TheKipster]

Hi everyone,

I'm at the end of my ideas! So hope one of you can help

Basically, my radiators are not hot enough. Forgive my non-technical terms, but I have a boiler & tank in my airing cupboard, two tanks in the loft (I believe to be overflow tanks or something), and a separate pump and control system in the airing cupboard, thermostat outside the cupboard in a different room.

The thermostat is always on, it's set at 23 at the mo but the "click" occurs at around 16 celsius. The pipes in the cupboard are scolding hot. As far as I know that's what temparture the radiators should be. But they ain't! So I don't think it's the boiler. I insulated all the pipes in the cupboard at the weekend and it made a little difference but not much...

The pump is a Grundfos Super Selectric 15-60, which allegedly should be used for larger domestic systems. It's on the top speed too. So in theory that shouldn't be the problem. I have 4 radiators upstairs and one downstairs. The downstairs one never feels like it's on though, which may be an indication the pump is finished???

Not sure what else to say, sorry for banging on a bit, I always find more info is better then less...

Chris.

 

[gas4you]

Is the small tank in the loft full of water?

If you bleed an upstairs rad do you get water out?

You need to prove the pump one way or the other. Is it spinning? Are the pipes either side of it hot?

Do you have any motorised valves in the airing cupboard?

 

[TheKipster]

Hi Dave,

Cheers for the lightning response...

1. In the loft the smaller higher one is about half full, the bigger one is about 3/4 full.
2. Not entirely sure how to bleed a radiator. Am very new to this thing...
3. Yep, it's spining. And when I change the speed it gets quieter/louder. The pipes either side are very hot. Although, on one side. There are two pipes that go up to the loft (presumable in some sort of circuit), and they both lose their heat half way up the pipe.
4. No motorised valves. A few red taps to be turned but none motorised...

Chris.

 

[gas4you]

1. In the loft the smaller higher one is about half full, the bigger one is about 3/4 full.

Good

2. Not entirely sure how to bleed a radiator. Am very new to this thing...

You need an air bleed (radiator key) and on one end of the radiators (or sometimes on th backs if they are round tops) you will see a little square metal pin head. Put rad key on this with tissue under it and undo slightly until you hear air hissing out ow water appearing.

Yep, it's spining. And when I change the speed it gets quieter/louder. The pipes either side are very hot.

Sounds ok but pumps can spin but not circulate occasionally.

There are two pipes that go up to the loft (presumable in some sort of circuit), and they both lose their heat half way up the pipe.

These will be the expansion/cold feed (15mm probably) and the open vent (should be 22mm)

A few red taps to be turned but none motorised...

Check these are opened, but if you could identify the by-pass if it has one then shut this for now.

 

[bengasman]

Open vent system with cold radiator downstairs could well be soiled. Look in f&e tank, should be the smaller of the 2. If water is dirty or bottom of tank covered with dirt, it is probably in need of a clean.

 

[Andy165]

what type of boiler do you have... is it a back boiler behind the fire? What clock/ programmer do you have.... does it give hot water only and heating/ hot water together and is the hot water working ok? Could be you need to throttle back the hw circs to divert more heat around the heating circs.Has the problem just started or is it an ongoing problem? More info. please

 

[TheKipster]

Hi All,

Cheers for all the suggestions, I shall check out what I can after work tonight and report back. ie all the valves & the f&e tank..

Andy, the programmer gives the option of hot water only, none, or both hot water & heating. The hot water is fine. I don't think it's the boiler as the pipes around the boiler are hot as ba***rds. I guess it's been happening since I switched it back to both heat & water. But only now I'm starting to feel it as the weather is getting colder.

Got another few ideas too. Will turn off all the radiators, turn one on, see how hot it is, and turn em on in turn and see what happens.

Will also check valves either side of the pump to make sure they are all fully open...

 

[TheKipster]

OK...

You need an air bleed (radiator key) and on one end of the radiators (or sometimes on th backs if they are round tops) you will see a little square metal pin head. Put rad key on this with tissue under it and undo slightly until you hear air hissing out ow water appearing.

All done, water came out straight away. No air in the system.

Check these are opened, but if you could identify the by-pass if it has one then shut this for now.

Err... bypass? Which one will that be? There is one on the 15mm pipe you mentioned which is currently open. The one going up to the loft. Would that be the one???

Open vent system with cold radiator downstairs could well be soiled. Look in f&e tank, should be the smaller of the 2. If water is dirty or bottom of tank covered with dirt, it is probably in need of a clean.

Water is clean but there is dirt at the bottom, probably 2/3 mm thick. So I guess that needs a clean. How would I go about cleaning it? Is it a case of somehow empting the tank or is there are more civilised way?

btw, just turned off all radiators bar one, and the temp of that one is the same as before...

Cheers for all the help guys... Any further suggestions???

Chris.