Central Heating makes a rattling/gurgling noise

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Hi guys...

For the past few weeks, our central heating has made a weird rattling/gurgling noise at around 5am every morning. It's really starting to annoy us now, because it's waking out child up (whose room is just opposite the water tank/pump), and he's refusing to go back to bed...

So, am hoping that you experts can help me to get it sorted :)

Anyway, some information...

We have a megaflo (dunno which version or anything) water tank, which at the time of the rattling, I noticed was sometimes leaking water out of it's overflow. Following the instructions, I emptied the tank. Now, the water is not leaking in to the overflow (that I've seen at least), but the rattling noise is still coming on. So, we heard it the other morning, and I went in to the tank to take a listen. After searching for the location of the noise, it appeared to be coming from the area where the pump was. We have a grundfos alpha+ pump, and from what I remember when I looked, I think the setting for the pump was on variable (can't remember 100% though).

Anyway, I had a look and found this thread on the forums. Seems like someone who had a similar thing?! But, I just wanna know exactly where I need to check.

I will take some pictures of the pump tonight and post them when I get a chance. Hopefully this will help you to help me :) But is there anything that I can do to try and reproduce this?! Would it just be a case of getting the hot water/central heating to come on, then I can go up and ascertain exactly where the noise is coming from?

As you can probably tell, I am rubbish with central heating/plumbing jobs :p But hopefully we'll be able to sort this easily :)

Many thanks in advance.

David
 
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could be air in the pump possibly - try venting that first

Suppose it could be me being ignorant, but I have no clue on how to do that? What would I need to do? Or, is that what I did when I emptied the tank?! Basically, the instructions (and what I did) on the boiler told me to open the lowest tap in house, and then turn a valve somewhere on (or near to) the water tank. This then drained the water. The tank then filled up. This stopped the overflow (or tundish as I've found out by searching :p) from leaking water... So do you mean to do something else?!

could be lack of water in the system :idea:

I wouldn't think so, but how would I check that?

Many thanks :)
 
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Here's some pictures of the boiler room/pump... You'll have to excuse the mess in the cupboard :p





 
if you bleed the highest radiator in the house, does water squirt out forcefully and without dying away?

I dunno yet, will give it a go tonight... What does it mean if it does do that, and what if it doesn't?
 
sorry for such a long delay in replying. Haven't had a chance to bleed the radiotors until the other day, and have been so busy with work/home that I haven't had chance to come back on the site...

Anyway, found one of the radiators was only getting hot at the bottom, and was cold at top. So, bled that radiator first. Air came gushing out, but no water came at all... Went round all the other radiators on this floor, and had no air coming from any of them, but no water came out from them either... I dunno whether this is because we live in a 3-floor house. Went down to the middle floor, bled all the radiators on this floor, and there was no air come out of any of them, but a little bit of water came out of each straight away (until I stopped). Same result with the bottom floor.

This morning, I checked, and the radiator that was only cold at the bottom was hot all the way through, and we didn't hear any rattling/gurgling this morning. But that could just be an issue in that we were fast asleep, so missed the noise :p hehe.

Will keep an eye on it over the next few days, but hopefully it was just the air in the radiator that was causing the noise?!

Is everything OK in the fact that water didn't come out of the top floor radiators though? As I'd have thought that water should still come out of them?

Many thanks again guys :)
 
yes, it indicates that you have a problem with the feed of water to your system.

Usually this happens when you have an open-vented system, with a small Feed & Expansion tank in the loft. Sediment builds up in the feed pipe from this tank and eventually causes a blockage. From your description it sounds as though possibly draining air out has caused enough of a pressure difference for water from the tank to get down and top it up. Sometimes the float valve, if very old, sticks and jams so it does not top up the tank. In this case it should be replaced.

What you should do:

Go up in the loft. Find the F&E tank (about 18"x12"x12") Look inside. Does it have a lid? Has it got water inside? When you push the float down, does more water come in? Is there mud, drowned wildlife, bits of insulation or other rubbish, at the bottom? Is the contents of the tank like slime, or carpeted with mould?

If the tank seems OK, water clean, valve working, no thick mud, sit up there with your torch and ask someone to drain a pint or more of water out of a drain cock or bleed valve. You should observe that the water level of the F&E drops by about a pint; the float goes lower, the valve opens, and the valve tops it up to the old water level. However you may find that some or all of this does not happen. How old is the system?

I can tell you what do do once we have identified the cause of the problem.
 
yes, it indicates that you have a problem with the feed of water to your system.

Usually this happens when you have an open-vented system, with a small Feed & Expansion tank in the loft. Sediment builds up in the feed pipe from this tank and eventually causes a blockage. From your description it sounds as though possibly draining air out has caused enough of a pressure difference for water from the tank to get down and top it up. Sometimes the float valve, if very old, sticks and jams so it does not top up the tank. In this case it should be replaced.

What you should do:

Go up in the loft. Find the F&E tank (about 18"x12"x12") Look inside. Does it have a lid? Has it got water inside? When you push the float down, does more water come in? Is there mud, drowned wildlife, bits of insulation or other rubbish, at the bottom? Is the contents of the tank like slime, or carpeted with mould?

If the tank seems OK, water clean, valve working, no thick mud, sit up there with your torch and ask someone to drain a pint or more of water out of a drain cock or bleed valve. You should observe that the water level of the F&E drops by about a pint; the float goes lower, the valve opens, and the valve tops it up to the old water level. However you may find that some or all of this does not happen. How old is the system?

I can tell you what do do once we have identified the cause of the problem.

The system was put in when the house was built, so is just over 4 years old...

As far as I remember seeing when I've been up in to the loft, there is no water tank there. I remember my parents old house (think was built in 1940's, not sure when the water system had been done last though), they had a tank in there like what you describe. It's a black box iirc, roughly the dimensions you said...

But, in our loft, there's nothing like that that I remember seeing...

From the pictures I posted above, if you look at the first picture, there's a little red tank, about the size of a football (maybe a bit bigger, and more oval shaped), which I think is some sort of pressure tank... But, I think it's a self-contained system...

Will have a check in the loft and see, but anything else I should look for?

A colleague of mine when I was speaking to them, said to try and bleed the radiators on top floor whilst the heating was running, as this would cause the water to pump and fill up the radiators, but would this not cause extra air in the system?

Thanks again
 
there's a little red tank, about the size of a football (maybe a bit bigger, and more oval shaped), which I think is some sort of pressure tank...
Ah, my mistake, if that is the case, it is not an open-vented system with an F&E tank. All my suggestions were wrong :oops:

You should find your boiler has a pressure gauge on it, and near or underneath your boiler will be a filling loop, probably a flexible hose with a control valve at each end, used for re-filling and re-pressurising the system.

However I will say that i can't see the pressure vessel you mention.
 
Are you sure that the pump is operating? Just because it vibrates doesn't mean it's working. They are very prone to impeller shaft breakage due to metal fatigue. That would account for the noises and why you get no water squirting out on the top floor when you bleed the rad.
 
They are very prone to impeller shaft breakage due to metal fatigue.
get the f*c are they

That would account for the noises and why you get no water squirting out on the top floor when you bleed the rad.

you'll still get water out of any air vent providing ithas water/pressure.
its a pressurised system a faulty pump won't stop that as you should bleed a system with the pump off anyway.
 

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