Leaking aavs on central heating system?

[Prenzie]

Hello, please bear with me, as I am new to forums. I have had installed a Worcester Bosch (oil fired) Greenstar Heatslave external boiler, nearly a year ago. There are several problems and I wondered if they might be connected. I have had the manufacturer out three times and a plumber to check the pipe work, but so far no joy.

There is water leaking through 3 ceilings which are directly under two vents in the roof which I believe to be automatic air vents. The roof timbers are sopping wet. At the same time, the boiler pressure levels keep dropping to nearly 0 bar and the system has to be repressurised every few days. The radiators sound like Niagra Falls when the ch system is turned on and the hot water is not continuous and often turns cold in the middle of a shower. Turning a tap off and then on again usually starts things going. Are the aavs likely to be venting water as well as air and in doing so emptying the system and resulting in a loss of pressure causing the hot water to be inconsistent? Are they all inter-connected? Could this be a never ending circle?

Would I be better off having manually operated air vents?

Hope someone can give me a guide. I have tried to find someone who will survey the whole system (boiler, pipe work, rads and taps) but this doesn't seem possible. I can have the boiler maintained (although at the moment it is still under warranty) or I can call someone in and ask them to fix a leak. But I don't seem to be able to find a service where the whole system can be looked at. If there are any plumbers/heating engineers reading this - is there such a service?

 

[GQuigley67]

I don't see why someone can't survey your system and diagnose the problem.

is it a sealed system ? I'm guesing it is, I dont work with oil but in a sealed system with loss of pressure the boiler doesnt work and this will effect central heating and hot water.

the AAVs may be faulty, but for all of them to be faulty seems unlikely, if you are repressurising every couple of days then it seems like a bad leak to me. Get someone out to have a look at it, and diagnose the problem.

 

[SimonG]

Worcester won't be bothered about the problem. Everything you are describing is down to the loss of pressure and not an issue with the boiler.
I'm a big fan of auto air vents but in this instance I'd be tempted to swap for manuals and see how you go.

Also worth checking if you are having water leaking through the pressure relief valve, tape a bag or small plastic bottle over the end to check if its dumping water back out. Unlikely though due to the water coming through the ceiling, but a simple one to check.

Should be as easy as getting somebody in to locate and rectify leaks, problem solved.

 

[chrispow01]

I had similar problem with one of my customers auto air vents although they were several years old. They leak quite badly when they go and his were both leaking together. As mentioned before the resulting pressure loss will affect boiler performance. Sounds like yours have gone there and need replacing with manual type.

 

[Prenzie]

Thanks so much for your help. I am not absolutely sure if it is a sealed system or not. I think it is sealed, because on an open vent system the pressure gauge is not used and on my system it is in use. I have had someone out to look at it, but they have just refilled the system, bled the radiators, checked the system is full afterwards and then said it will be OK. That was just a few weeks ago and since then, the problem keeps recurring. I have called them out again, but they can only give me an appointment in three weeks and meanwhile, my newly painted ceilings have once again been ruined. I have turned the heating off in the hope that it won't happen again until fixed, but I am not sure if the hot water system uses the AAVs.

 

[GQuigley67]

it is a pressure loss due to a leak, which will effect both central heating and hot water. Get them replaced with manual air vents asap as the more it leaks the more damage you will cause, you can ruin the wood and your ceiling could collapse this just happend to my girlfriends mums house due to a leak from the roof building up and their ceiling has fallen down

 

[SimonG]

It will still lose pressure even with the heating off. There are valves internal to boiler that could valve off the central heating flow and return until leak is fixed but you need somebody who knows what they are doing.

I take it the water wasn't coming through the ceiling when you had somebody out?

 

[Prenzie]

Thanks so much for getting back to me. I think you are right about Worcester, but I was uncertain if the supply of hot water which is very inconsistent is connected in any way with the heating system. I know nothing about heating and plumbing and if the AAVs in the roof are reducing the pressure in the heating system, does this mean the hot water pressure is also effected?

Is the pressure relief valve the one I am using to top up the system? If so, this is not leaking at all and is near the boiler, not in the roof. Near the leak in the roof I can only see two vertical pipes and they each have slightly different valves or vents at the top. I am calling these the AAVs and think they are the cause of the leak. If you think it it would be a good idea to go for manuals, I will have a go. The guy I called out to fix the leak re-pressurised the system, bled the radiators, checked the system again and then said all would be OK. But since then it has leaked again and the system has had to be filled up several times. Difficult to get him back quickly, but I have tried, meanwhile I have turned the heating off.

 

[Prenzie]

Thanks so much. I am receiving so much valuable help. I am pretty sure now that I will have to insist on having manual AAVs. Am not sure if this will fix my hot water problems, but it is a first step. I already feel better about the problem and will be on the phone tomorrow to get the ball rolling.

 

[SimonG]

The pressure releif valve should be a 15mm copper pipe that has been run to outside so that in the event of over pressure (>3bar) it dumps the excess water outside safely. But it sounds very much like it is nothing to do with this.

Basically the water that runs round your radiators is the same water that is pumped through the plate heat exchanger that creates the hot water to the taps, so unfortunately turning off the heating will have no impact on the leak.

Make sure that when its fixed they top up with inhibitor, as if you have been having to top up every other day it will need some extra.

 

[Prenzie]

I will ring up tomorrow morning. I may have to get an emergency plumber in. My plumber can't come out again for several weeks. Thank you so much for your advice. If only I had had the sense to post this problem a few weeks ago, I wouldn't be in such an awful position. Thank you again, such valuable advice.

 

[SimonG]

Hope you get it sorted. Good luck.

 

[Prenzie]

I will check the pressure relief valve, but I suspect it's those AAVs! I had no idea the same water was going round the radiators that I was using in the taps! I go back a few centuries I am afraid when the water in radiators was awful black stuff. I don't know what inhibitor is, but I will certainly ask for it.

So turning off the heating won't help? I thought it only happened when the heating came on. That's is very important information and makes a difference to the urgency of the call out. You have been so very helpful. Thank you very much.

 

[SimonG]

Its not the same water as comes out of taps. It flowes through a plate heat exchanger which is layers of metal plates, through one layer passes the heating water, the next layer cold water which becomes your hot water, the next layer the heating water and so on. Difficult to explain without a picture.

 

[GQuigley67]

take a picture of the suspected suspects and we can confirm to you if they are AAVs or not.

You could also try putting a leak sealer into the system via one of the radiators, usually stops small leaks

 

[Prenzie]

Can't believe the problem will still continue with the heating switched off. What if I turn off the water at the mains at night? Will that help or will that cause even greater problems? Yes, the water was coming through three ceilings when I called for help. It was what had alerted me to the problem (I hadn't realised that the gurgling radiators and the lack of supply of hot water might be connected with vents in the house, I thought it was the boiler). The guy knew there was a serious leak, but said the problem would be solved by filling up the system. The company have been told that it has happened again, but have given me a three week wait. So I am going to have to use someone else I think. Thank you again (Simon?), you have been very supportive.

 

[Prenzie]

Your explanation about a plate heat exchanger makes perfect sense. I am learning more every minute! At least I am not drinking my radiator water! Thanks again, you're a star!

 

[Prenzie]

Hello, Going to try to add a couple of photos to this. It's all a bit new to me, so hope it works. One is a close up (although I couldn't get the markings to come out clearly without standing at such a dangerous angle that falling through the roof hatch was an option!), the other is showing the vertical pipes. I hope they are good enough to confirm that they are indeed AAVs! Will keep a leak sealer in mind too. Thanks for keeping in touch.

Sorry, no good I am afraid. I was stuck with a URL link and hadn't a clue what to do! I have the photos in Photoshop, but am stuck from there on...... Really sorry I haven't tried to upload a photo before. I will do some research and see if I can get more succcess.

 

[Prenzie]

Having another go with the pics! Hope this works.

 

[wheeto]

Hello, yes those are AAVs. You could try closing the vent guards (by turning the small screws on the top clockwise) as this may slow or stop the water escaping. It will also stop the vents working, so you'll still need to get the system attended to for a permanent fix.

 

[Prenzie]

Hello, if I close the vents as you suggest, won't that be the same as having manual vents put in? Are you saying that there is likely to be another underlying problem with the system which is causing the air and water to escape? If that is the case, putting in manual vents won't solve the problem, but I will be back to square one, not knowing how to get the system checked out for faults. I can get the boiler looked at by any number of people and I can get plumbers to come out and fix things that have gone wrong, but no one seems interested in 'checking the system' to find a fault. Who should I be asking for? A plumber, a heating engineer......

I have an appointment with Worcester Bosch booked for Tuesday because I thought the hot water problem was a boiler problem. Do you think I should cancel the visit? Does it sound to you as if I have a problem with my boiler? Other people who have answered my post, have suggested that the boiler isn't at fault, it's probably the AAVs leaking, causing the water pressure to drop, causing the radiators to empty and causing the pressure to go down which in turn interrupts continuous supply of hot water.

Do you think I have misunderstood? Thank you for your help.

 

[GQuigley67]

there wont be anything wrong with your boiler, it is only a pressure loss problem, the boiler needs pressure in it to operate. Is there water coming from the AAVs ? are you sure it is them that are leaking ? if its them thats leaking then that is your problem.

 

[Prenzie]

I have seen the occasional bead of water sitting beside one of the AAVs and the timbers in the roof which are getting wet are directly underneath these AAVs. I have checked all the pipes around them and can't see a leak anywhere else. Would it make sense to loosely wrap some kitchen roll round the valves and tie a poly bag round the outside (with some perforations for air to escape) and then check every few hours to see if the paper is getting wet?

Thank you for your help. Wish you worked a bit nearer!!!

 

[paulnwales]

If i remember correctly the blow off will be on the right hand side of the boiler, it will poke out of the external cover on them. The fact the water is coming through the cieling is obv telling you the location of the leak. Personally if i was you id get up to the vents when the water is leaking and you will prob find the leak... Good chance the aav have not been fitted correctly, most are only screw in.

 

[Gray0689]

If the plumber you got didn't check to see where the water was coming from he a joke don't get him back the pics show the water been leaking for a while wood soaked
Get a different plumber in to sort out problem as said manual valves or good flanco ones
You can cancel Bosch the boiler not the problem and they may charge you as not there product that then problem
What area are you in as there may be a plumber on here that could sort the problem for you