Combi bolier & rads

[IceBoy]

Hi All,

With the weather getting a little fresher, I thought we would try the cntral heating out.

The complete system is only a couple of years old but I had the following problem:

• some rads are really hot, others are warm and some are just tepid.

All the rads have thermostats on one end and a little knob with + or - on the other end.

FYI - 16 rads and a large combi

What can I do ?

IceBoy

[2marlin]

have you bled the radiators - they may be half full of air...

[paulmurr]

As above, sounds like they need bled.

[james_tigerwoods]

Isn't there something you're supposed to do to regulate the flow from the first radiator to the last - the first getting a more restricted flow (so all the hot water doesn't go to that one) and the last getting all the flow?

I seem to remember (when I used to remove radiators for decorating) that the thread on the valve without the thermostat had to be turned "so far" - there's something you can get for radiators to check the temperature on them to check this.

At least, that's how I remember it anyway....

[rocksteadyeddie]

"I feel the need. The need to bleed"

You'll want one of these:

[Lord Flathead]

IceBoy said:

Hi All,

With the weather getting a little fresher, I thought we would try the cntral heating out.

The complete system is only a couple of years old but I had the following problem:

• some rads are really hot, others are warm and some are just tepid.

All the rads have thermostats on one end and a little knob with + or - on the other end.

FYI - 16 rads and a large combi

What can I do ?

IceBoy

Change your login name from Iceboy to Toastyboy.. that should sort it

[.:ian:.]

Might also need balancing, all the ones that are too hot, give the + - nob a quarter turn the - side, all the ones that are too cold give a quarter turn to the + side. Rinse and repeat.

Theres a proper way that involves a IR thermometer and adjusting each rad to allow for a 10 degree drop across it, but with 16 rads you will be there a while..

[davido140]

james_tigerwoods said:

Isn't there something you're supposed to do to regulate the flow from the first radiator to the last - the first getting a more restricted flow (so all the hot water doesn't go to that one) and the last getting all the flow?

I seem to remember (when I used to remove radiators for decorating) that the thread on the valve without the thermostat had to be turned "so far" - there's something you can get for radiators to check the temperature on them to check this.

At least, that's how I remember it anyway....

Agreed, if the return valve is not open far enough then the water in the rad will go cold and cannot be replaced by hot water fast enough.

It's a bit of a black magic to set them up right, all depends on how far along the system the rad is and what type of plumbing you have to your radiators. All I really know is when you remove a rad always remember how many turns it was to close the return valve and open it again by the same number so you dont balls it up!

[Road2Ruin]

james_tigerwoods said:

Isn't there something you're supposed to do to regulate the flow from the first radiator to the last - the first getting a more restricted flow (so all the hot water doesn't go to that one) and the last getting all the flow?

I seem to remember (when I used to remove radiators for decorating) that the thread on the valve without the thermostat had to be turned "so far" - there's something you can get for radiators to check the temperature on them to check this.

At least, that's how I remember it anyway....

There is indeed, but I would imagine that if it has worked fine for two years then it is not this.

[james_tigerwoods]

Woohoo - I'm right (ish) about something

I did, however, stumble across this which is what I was thinking about:

http://www.homebuilding.co.uk/feature/how-balance-...

Not that it might be the problem, but it's what I was thinking of...

[IceBoy]

I did bleed the air off but there was not too much in there !

So it must be a balancing problem ?!

Guess what I'm going to attempt at the weekend !!??

IceBoy

[Ray Singh]

+1 for balancing.

I had exactly the same thing with my rads last year.
Get yourself a decent plumber over and he should charge no more than 1 hours labour to sort this for you.

[st_files]

Is it just me or do other men feel very manly when they tell their woman/lady/bird that they'll bleed the radiators. I guess its how the stone age caveman felt as he says he's just popping out for a week to stalk, hunt, kill, skin & gut dinner.

[james_tigerwoods]

Ray Singh said:

Get yourself a decent plumber over and he should charge no more than 1 hours labour to sort this for you.

Personally, I'm not saying it is that, but it sounds like it might be.

I would, however, take the above advice and get a plumber to do it - it'll reduce the risk of making it worse, raising your blood pressure and increasing your swear vocabulary - and, eventually, calling a plumber in anyway....

Or - you could do the moron thing that I did once - Removed a bathroom "ladder" radiator for decorating and put it back on. The heating then packed up and there was no heat (it was December, so the then OH was not amused) - several hours later, I realised that when you A:Remove a load of water from the central heating, you need to B:Put it all back - several sheepish seconds later while I found the relevant valve, I increased the pressure to the system and achieved in 45 seconds of common sense that I failed to achieve in 3 hours of idiocy and swearing.

Edited by james_tigerwoods on Monday 19th October 11:40

[Zelda Pinwheel]

You might also need to increase the pressure in the system, eventually the pressure drops to a point at which bleeding will have no effect whatsoever. Our system was off the bottom of the scale when we checked it recently, having had the same problems as you. There's a helpful video at http://www.ultimatehandyman.co.uk/bleeding_a_radia... which explains where to find the top up valve etc.

[james_tigerwoods]

st_files said:

Is it just me or do other men feel very manly when they tell their woman/lady/bird that they'll bleed the radiators. I guess its how the stone age caveman felt as he says he's just popping out for a week to stalk, hunt, kill, skin & gut dinner.

No, no - I feel manly with a BBQ.

Man. Fire. Ug.

[HellDiver]

Could also be sludge clogging the pipes if it hasn't been used for a long time.

What colour was the water when you were bleeding the rads? If it was brown or black you're likely going to need to add some sludge remover, the flush the system a few times.

[homeimprovements]

Ice Boy

first thing to do is ensure your heating system is filled up to 1.3 bar ish and then bleed your radiators.

Then there are a couple of things you need to do.

Unscrew the heads off the thermostatic valves on the rads that are not getting hot. There will be a small pin sticking out . Give it a little tap. You should be able to see it move in a out as you do this. The valves can easily stick if the heating hasnt been on for a while. Have been to seven houses last week with this problem. Then screw the head back on and test.

If this doesnt help. Turn off the radiators that get hot and see if the others now get hot. This basically just increases the flow pressure to the others and if it is air in the system this is just pushed into the open rads which can then just be bled Once they get hot turn them all on and hopefully they should all get hot.

If not it will be a balancing issue as mention above but if the system has been previously fine then it is unlikely to be this.

Or just call in a plumber. Should be a maximum of about 1hour if the heating is already up to temp when he arrives.

If you need any more help just ask