Air in the CH/HW pipesystem?

[TonyK81]

Hi,

We have a weird situation with our HW/CH system. When there's a demand for either of them, the boiler tries to switch on, I see the green light (firing the gas) switching on for approx 10 sec, then switches off. At the moment, we have the controller in the following position:
- HW always on
- CH off (controlled by wireless room thermostat)

Compartments:
- Honeywell ST400C main controller
- Digistat SCR + RF3 wireless thermostat controller
- Honeywell V4073 3-way valve
- L641A Cylinder Stat
- Worcester Greenstar 12Ri boiler
- Grundfos pump

The pump makes a continuous sound as if it's working, but not the usual sound it used to make. I have a feeling that there's air in the system. Why? A couple of days ago I realized that one of the radiators was pretty cold, so I used the key and emptied the air from it. I had done that again just 1.5 month ago.
Furthermore, there is a small "overflow" pipe right next to the tank (right after the B-position of the valve). Whenever I unscrew that (there's a tiny hole there), there's no water coming out of it. It's completely dry. Also, the last couple of days we would hear weird noises from the pipesystem. As if water is dripping inside of them, though there is no leakage. So I believe it's some air in the system, and the dripping sound is from the water moving around inbetween air masses.

My guess is this: The pipe leading to the boiler has air, so the boiler kinda realizes that and switches off. I also guess that the pipe coming back from the boiler to the pump has air (it's completely cold at the moment), and the pump just runs without pumping water really, but it's just air inside it. That's why it makes a different kind of noise. This is the input pipe AB. Then output pipe B which leads to the tank, probably only has air now, that's why the overflow pipe is so dry.

Question is, what do we do if there is air indeed? Do we have to call a plumber for this issue? Or is it a boiler problem, and we have to call a gas engineer instead?
More importantly, how would air come into the system? What malfunction would that indicate?

As a note, we keep switching on and off the boiler regularly, since we generally had some issues with the CH/HW system, which we haven't completely solved yet
(that's a link to the previous issue we had:
http://www.ukplumbersforums.co.uk/c...-stopping-honeywell-v4073-greenstar-12ri.html )

Any help is very much appreciated, since I'm afraid we're gonna run out of hot water very soon, as soon as the tank empties!

Thanks

 

[TonyK81]

To add something I just noriced. The pump started making more noise now. I think it gets a signal from the cylinder stat for demand for HW, since the water temperature inside it must have fallen below the cylinder stat limit. The boiler status light is flashing continuously.

The boiler user's manual says the following.
Indication: Fast flash
Fault: Volatile lockout (sensor, fan or code plug)
Possible Solution/Check: Temperature sensor (8000 - 20000Ω). Wiring/connections to sensor. Fan/cable/connections. Code plug fitted.

Does that help at all? Any idea what these things mean?

 

[Gray0689]

What pressure is in system at gage at combi??

 

[TonyK81]

Hi Gray0689,

Hm, I'm not sure what you mean by "gage at combi".. Where can I read the pressure from? If I need to do that from the boiler, all I can say is that there's not much I can read from outside, it's only the ON/OFF switch, the boiler thermostat, and the indicator light. The boiler thermostat is set to approx 80% of the max value.

 

[Gray0689]

How do you know what pressure you are putting in to system when you to it up??

 

[TonyK81]

Hi Gray0689,

I'm still not sure what you mean. I'm not a plumber, by the way, just a home owner. Don't have much experience with plumbing, to be honest, so I have no idea how/where to read the pressure from. From all the compartments I mentioned in my first post, there's nowhere I can see an obvious pressure reading. At least, not as far as I can tell..

Thanks

 

[Gray0689]

Sorry reread your post I guess you have an open vented system ie tank fed

 

[chrispow01]

I;d check your pump tony, that would explain your symptoms, boilers firing on demand but with no circulation it gets up to temperature in seconds then shuts down, it could also be airlocked in which case vent all rads and any air vents, circulate the pump to try to move air around then vent again. Check your feed and expansion tank, i assume its gravity fed, make sure its not sludged up and repleneshing system with water. good luck

 

[TonyK81]

Hm, I'll try to turn all heating on again, and see what happens. Out of all the radiators, it was onl one that I noticed had air inside it. The pump seems to be working, it gets pretty warm when turned on, and does make an "operating" sound. So I don't think it's not working.. It does sound different though, as I mentioned earlier.

I'll turn the CH on now, and see what happens. Will update later on.

Thanks Chris.

 

[TonyK81]

Well, turning the CH on didn't change a thing. Radiators are still cold, there's no water circulation. If I try to vent the radiators, there's no air nor water coming out, which kinda makes sense if there's no water circulating - nothing is pushing either the air nor the water inside them.
However, now the overflow pipe next to pipe B of the valve, is spilling out some water once I un-screw it.

A friend suggested that maybe someone did some works in the neighbourhood and cut the water supply, or something like that, so it's not simply just air in the system, but rather complete lack of water. (Is it possible we have a different supply for the potable taps - ie in the kitchen- and the one that goes into the boiler??)

Thanks again,
Tony

 

[Gray0689]

Well, turning the CH on didn't change a thing. Radiators are still cold, there's no water circulation. If I try to vent the radiators, there's no air nor water coming out, which kinda makes sense if there's no water circulating - nothing is pushing either the air nor the water inside them.
However, now the overflow pipe next to pipe B of the valve, is spilling out some water once I un-screw it.

A friend suggested that maybe someone did some works in the neighbourhood and cut the water supply, or something like that, so it's not simply just air in the system, but rather complete lack of water. (Is it possible we have a different supply for the potable taps - ie in the kitchen- and the one that goes into the boiler??)

Thanks again,
Tony

No
Is your heating tank fed ie header tank on roofspace ??

 

[TonyK81]

Hm, the heating tank is inside tha flat. I haven't figured out where it's fed from, since it has like 4 pipes coming in/out of it, and I'm not sure which comes from where, or where it goes. At least not for all of them. I can tell what two of them are for: valve pipe B is input for HW, and I can also tell the one going towars the bathroom.
As far as I know, there is no other tank on the roof top. We're also the top floor, and the ceiling is sloped, so I'm pretty sure there's nothing on the roof.
Does that answer your question? If not, I may misunderstand what you're asking me.

 

[Gray0689]

Can you post pics?

 

[TonyK81]

I'm afraid not right now.. The whole waterpipe system is inside my flatmate's room, and he's sleeping now
Probably tomorrow I should be able to.

 

[Gray0689]

Ok post pics tomorrow

 

[chrispow01]

Tony, your goin round in circles there mate, i still say its the pump, the change in noise is a big clue, i had one the other week, everythin was pointing towards the pump but it was spinning (take the centre screw out and lightly put a screwdriver in to the spindle to check) Anyway, changed it and problem was solved. I also think you may have sludge in the system, did you check the f + e tank, the feed pipe often gets blocked there and will also cause related problems.

 

[TonyK81]

Hi Chris,

I had a look at the pump, but I'm not sure what I'm looking for? I removed the middle screw, there was no water coming out of it, if that says anything. I was able to manually rotate it anti-clockwise (as the arrow suggested). It was free to move (but I wouldn't call it loose). I had switched the power off while trying this, though, I didn't wan to risk doing any damage since I wasn't sure of what I was looking for. In general, the pump does make a working sound. The difference in the noise that I mentioned is probably because there's no water inside it.

About the sludge, I'm not sure how to check it. I'm also not sure of what you mean by feed + expansion tanks. I can only see one tank, the one that's in our flat. I'm not sure I can open it, though. I'm on a top floor, and I believe there's no tank on the rooftop (since it's sloped). So what would that make my tank? A feed one or an extension one?
The input pipes seem to be coming from the top, so I'm not sure if sludge would climb all the way up, and into the system (we're 4th floor).. could it?

I'm attaching a photo here, for Gray. Not sure if that helps. I'm not a plumber, but the whole pipesystem seems too complicated for me. There's also another pump (the black box at the bottom left), which pumps the HW from the tank to the bathroom. The tank has 4 inputs/outputs. 2 on tha left lower side, as you can see, one on the top (which splits up immediately in 2 pipes), and there's also one more on the right bottom side, from the back. That's the pipe you see on the further right side going down. The boiler is in the kitchen.



Thanks again for all the help.
Tony

 

[Gray0689]

It sounds like a blocked cold feed you will have a f&e tank somewhere feeding your system
Think you had better get a plumber in to look at it
If you post where you are someone on here may he close bye

 

[TonyK81]

Hm, so if I'm right, there is one external pipe coming into the flat. That splits up in 2:
- cold water, going to the kitchen and the cold water in the bathroom (this goes through the black pump)
- a pipe going to the boiler in the kitchen. This heats up the water and comes back to the 3-way valve. The HW goes into that big green storage tank. The boiler in the kitchen must have a tank to heat up the water, obviously. I believe that the pipes going forth and back from the boiler are going through some cavity pillars.

Still not sure if there is another f&e tank anywhere else, I can't see the room for that. So, the blockage must be in the pipe that sends the water to the boiler (or the one coming back, towards the Grundfos pump). That's why the pump is empty, there's no water coming in, and doesn't sound like the pump is the issue, since it's not pumping water cause simply, there's no water in it.
I guess there's not much I can do by myself then, I will have to get a plumber in. I will try to get some contacts from the neighbors then. I'll post again if there's any other update.

Many thanks again,
Tony

 

[TonyK81]

Here's another thought.. I can see where the CH water comes from. It's pipe A from the 3-way valve. But I don't know where it goes to. it's supposed to be circulating, but the only "input" I can see is the 3-way valve. So, where does it end up to? Does it go back to the boiler to be re-heated? If that's the case, is there any chance that the CH system had so much air inside it, that it turned out to be gathered in the boiler, and then all the way back to the pump? Should there be a re-filling valve that will allow some fresh water to come into the whole system?

Or am I talking nonsense here?

 

[chrispow01]

Your nearly there tony, the flow from the boiler comes directly to the red pump in your cupboard, from there it goes to the silver mid position valve, pipe AB, pipe A goes off to the Central heating where it circulates round and returns back to the boiler to be reheated as u guessed, pipe B goes into the cylinder, through a coil to indirectly heat the cylinder water, this then comes out the bottom of the cylinder and also returns to the boiler. There is normally a Tee on this return pipework going up to the Feed and Expansion tank (this is about 18" x 12" x 12" black plastic tank with a ball valve in) this replenishes the system with water. The system could well be airlocked as you guessed but the cause of this would also have to be remedied. As gray said, u may have to get a plumber in to sort it....

 

[chrispow01]

Sorry, the pump on the floor is for the shower, hot and cold in, hot and cold out, operates only when you operate shower!

 

[TonyK81]

OK!.. Interesting update!

I climbed up on a wall, where I figured there may be some cavity there, and behind a fake wooden board I discovered a whole tank!! So it seems you guys were right, there IS an f&e tank (or something else, I'm not sure how to categorize it). There is a black big tank, which is covered with a lot of plastic bags wrapped up in duckt tape. Next to it is a smaller red spherical looking tank, with a gauge below it. That's the one in the photo below.



(What does that make my heating system? Is it a Open Vented / Conventional System? Or an Open Vented / Sealed System? I checked these terms from here:
Glow Installations - CORGI heating and plumbing installations; our engineers fit boilers, combination boilers, central heating systems, megaflos (unvented hot water cylinders), underfloor heating and secondary hot water circuits. )

Now... I had everything switched off, and the gauge read 0 (out of max 4). When we switched everything on (meaning, switch on the power), I think it raised to 0.2. I think the meter reading is in bar.
Next to it, there was a switch, which from what I understood by reading diagrams and other stuff online, is the WRAS filling switch. I switched that on, and I heard a lot of water going through the pipes. Bubbling noises as well, and I got a feeling that some tanks started filling up.

We switched the CH and HW on, in order to have the most circulation possible. We did have CH and HW at the same time. The pressure meater reading started rising, pretty slowly, but steadily. After about 45 min, the reading was to 1.1. We tried switching the CH off, and after a while it dropped to 0.9. We switched it back on again, and reached 1.1 again. At that point (and since I was almost hanging there for an hour!), I decided it was OK to switch the WRAS off.

So, it's been 1.5 hours now. 10 minutes ago we started hearing that bubbly noise again. But now, I can confirm it was coming from the big black tank. There's a couple of pipes that go inside it (can't tell for sure since all the pipes go that way, I guess most of them pass below it and into a cavity wall). The bubly noise I heard sounded like water dropping from a tap in a pond of water. So I kinda guess that the black tank is not completely full, and one of those pipes drips water in it. That's the kind of noise it made. I checked the gauge and it read 0.6 bar now.

So what does all this mean? Towards the end, I checked the boiler and it was on, and since no CH was on, I guess it was demand for HW?... Does all this makes sense? I checked for a leak, but I couldn't find anything. And I assume that if it was a leak in a hidden place that we couldn't see, it must have come out in the flat below us, but the neighbours didn't say anything...

Any idea what may be the problem?

Many thanks again,
Tony

 

[TonyK81]

actually, to correct myself. Once the bubbly noise started, and I started checking the system status again, I think that at some point the bubbly noise stopped, and that's when the boiler fired up. At the moment I have shut everything down, cause I didn't want the pumps etc to keep going over the whole night, and having air come into the system again.

 

[chrispow01]

Right tony, you may have solved this problem. Weirdly you have a sealed CH system, with that Y plan arrangement you have in your cupboard you nearly always have open vented which is where u expect to see the black tank. In place of that you have the red expansion vessel, which takes up water expansion when the system gets hot.
Them gurgling noises are just the air and water sloshing round the system.
What u need to do is get rid of the air. VENT EVERYTHING, top up pressure again to 1 - 1.5 bar, vent again. Fire boiler, and u should be ok.
Big black tank is your Cold water storage tank, which supplies your hot water cylinder below and possibly your bathroom with Cold water. Ball valve inside, which is where u can hear the dripping from (they often drip)