Central Heating Issue

[James Stewart]

Good evening all, I'm having some problems with my central heating and hot water system.

Basically a couple of months ago our old boiler packed up, it was a Potterton Netaheat Electronic 10 - 16, the gas valve failed and our landlord had to replace the whole boiler.

We now have a Ferroli Optimax HE Plus18 0V, now this system has been installed for about a month and a half but since it was installed we have had a constant issue with getting air in the system, which can be easily heard bubbling through the radiators, when the heating is on. I have constantly been bleeding the system but it keeps drawing in air some how.

The engineer has been out several times to try and correct the issue he has changed the speed of the pump, changed the ballcock setting in the header tank, bled the system, adjusted the auto air vent, adjusted boiler settings and most recently replaced the pump which was just an utter joke. He decided to install the pump the wrong way round so that it pumped against the flow of the system. This resulted in extreme banging coming from the pipes.

That was rectified but we are still drawing in air.

Now I have had a wee look at the technical drawings for the boiler and have discovered that the feed from the header enters the system on the return side of the system, now going by the technical drawings the header feed should enter on the flow side.

I did ask the engineer about this but he said it was OK to plumb the boiler in this way, I didn't doubt him at the time because he is the expert but now I am thinking he is wrong.

I spoke to him again today and he has said he will move the header tank to a higher position to try and solve the problem.

I have tried to work out this problem and I have come to three conclusions on what the issue could be.

1. Is that the header is connected on the return and not the flow side.

2. The system is draining the header faster than it can be replenished. So how moving the header solves the problem I don't know.

3. It is the wrong boiler unit for the installed system, from what I worked out the old system was a gravity fed system and the new boiler shouldn't be used with a gravity system

So can some one please give me some input.

 

[WHPES]

Its plumbed up wrongly with the Feed and Expansion. Cure by converting to sealed system.

If someone tried something like reversing the pump flow to attempt to cure it I would question their competence.

 

[rhp]

Sounds like it's drawing air in down the vent, a photo or two of the boiler and the pipework (pump etc.) in the airing cupboard would be helpful.

 

[rhp]

If someone tried something like reversing the pump flow to attempt to cure it I would question their competence. someone tried something like reversing the pump flow to attempt to cure it I would question their competence.

Definitely !

 

[James Stewart]

Thanks for the replies, I will get some pics of the system tomorrow.

 

[Billy Bob Bob]

Definitely !

plus 2

 

[beneyresgas]

did they remove a air seperator above the old boiler? and how have they liked in the vent and feed ?

 

[James Stewart]

Sorry for being a bit slow in posting, been a bit ill. I have made this diagram to sort of show the system as it is installed.

The new bits are the boiler and the combined feed/expansion.

I'm sure someone should understand it, any questions to clear it up I will answer them.

Any help to explain why I'm still getting air in the system will be great.

Also my plumber has used plastic fittings on the expansion in the attic.

 

[James Stewart]

did they remove a air seperator above the old boiler? and how have they liked in the vent and feed ?

From what I know the air seperator was removed.

I don't know how the feed and vent have been linked but from what I see it is just one pipe that enters the atic space with the expansion branching off.

 

[doitmyself]

I have made this diagram to sort of show the system as it is installed. The new bits are the boiler and the combined feed/expansion.

That layout does not compy with the boiler manufacturer's Installation Instructions. They would be entitled to cancel the Warranty they give on the boiler. This shows how it should be connected - the Feed tank for the boiler is the one on the left.

 

[James Stewart]

That layout does not compy with the boiler manufacturer's Installation Instructions. They would be entitled to cancel the Warranty they give on the boiler. This shows how it should be connected - the Feed tank for the boiler is the one on the left.

View attachment 2792

Would that cause the problems with the air in the system?

That was the diagram I was comparing it to as well but thought I should ask just in case there was another way to install it.

 

[doitmyself]

Would that cause the problems with the air in the system?

That was the diagram I was comparing it to as well but thought I should ask just in case there was another way to install it.

In theory it should not cause your air problem. In any case you have a combined feed and vent, so this should reduce the possibility of air entering the system.

I see you have an Automatic Air Vent in the feed from the boiler. Is this at the highest point in the system, i.e above the top of the upstairs rads and the HW cylinder? Do you know what make/model it is?

 

[James Stewart]

In theory it should not cause your air problem. In any case you have a combined feed and vent, so this should reduce the possibility of air entering the system.

I see you have an Automatic Air Vent in the feed from the boiler. Is this at the highest point in the system, i.e above the top of the upstairs rads and the HW cylinder? Do you know what make/model it is?

We are in a first floor flat, so yes the AAV is at the highest point, I'm not sure what make it is, would a pic help?

 

[doitmyself]

I'm not sure what make it is, would a pic help?

Possibly. Has the valve been tested to make sure it works?

You said that you have constantly bled the system. Did you do this when the system water was cold?

 

[James Stewart]

Possibly. Has the valve been tested to make sure it works?

You said that you have constantly bled the system. Did you do this when the system water was cold?

Bled it when it was cold, heating up, hot and cooling down all failed as after each system bleed it had loads of air in it within 24 hours.

 

[James Stewart]

Here is the pic of the AAV


One thing I have noticed the wee black plastic bit on the top is loose, it can be lifted off easily.

 

[doitmyself]

Here is the pic of the AAV

One thing I have noticed the wee black plastic bit on the top is loose, it can be lifted off easily.

Is it actually on a horizontal pipe or has the picture been rotated through 90°?

 

[doitmyself]

Bled it when it was cold, heating up, hot and cooling down all failed as after each system bleed it had loads of air in it within 24 hours.

Does that mean you were bleeding it when the system was running? If so, that's not how you do it!

Bleeding should always be done with the system turned off and preferably when the water is cold. It's also a good idea to lock the motorized valves in the open (Man) position while bleeding.

Don't forget to bleed the pump.

Is there a bleed valve on the pipe from the motorized valve to the HW cylinder?

 

[James Stewart]

Is it actually on a horizontal pipe or has the picture been rotated through 90°?

Picture is rotated, sorry should have said

Does that mean you were bleeding it when the system was running? If so, that's not how you do it!

Bleeding should always be done with the system turned off and preferably when the water is cold. It's also a good idea to lock the motorized valves in the open (Man) position while bleeding.

Don't forget to bleed the pump.

Is there a bleed valve on the pipe from the motorized valve to the HW cylinder?

I have done it with system on and system off.

I haven't changed the valve settings when bleeding.

I haven't bled the pump as I don't know how to there doesn't seem to be any bleed valve on or near it.

There is no bleed valve that I can see on the pipe to the HW cylinder.

I will have a look at the pump and cylinder pipe again tomorrow to confirm this, but I doubt they will have it as the pipe work is original to the building which is circa 1970's

YOu are being an immense help with this problem. So far I am getting a better picture of how to possibly resolve the issue.

Just need to find out where the air is coming in though, thats the challenge.

 

[Blackcatgas]

make sure that the vent pipe rises 18" above the tank and drops down rather than resting on the tank and "in", does that make sense? Iam full of cider.

 

[doitmyself]

I have done it with system on and system off.

Bleeding must be done with the system off, i.e when the pump is not running.

I haven't bled the pump as I don't know how to there doesn't seem to be any bleed valve on or near it.

You bleed the pump by undoing the large screw in the centre of the label on the front. Hold an old towel or rag underneath as some water will escape.

 

[James Stewart]

Bleeding must be done with the system off, i.e when the pump is not running.


You bleed the pump by undoing the large screw in the centre of the label on the front. Hold an old towel or rag underneath as some water will escape.

OK I will try this later on.

Not holding my breath though. Just think that is other issues that we are not aware of.

 

[James Stewart]

Done what you all have suggested, got all the air out of the system while it was cold and off and valves open. Bled the pump and searched for a bleed valve on the feed for the HW Coil didn't find one. Once I had the air out I closed the valves and switched the system on and left it for an hour.

I then heard gargling from some of the rads and also some unusual noises from the pump, it sounded like air was in it. The system again sounded like it was filling with water or water was running somewhere.

I let the system cool and checked the rads again for air and they needed bled again.

Surely that isn't right.

I am going round in circles with this now.

 

[doitmyself]

Have you checked the water level in the F&E tank in the loft (It's the small tank)? It should be about 4 inches above the outlet at the bottom of the tank.

Check the ball valve works (press it down)

Check that water can enter the heating system as follows:

One person watches the level while a second person opens a drain tap (usually on a ground floor rad) and lets some water out. (Connect a hose to the drain and take outside.)

If the level drops and the ball valve opens before the level drops to about one inch from the feed pipe at the bottom, it's OK.

 

[easyt]

Definitely check F&E tank. I took a radiator off the wall about 15 years ago when decorating. After I put it back I tried to bleed it. Air came out but it just wouldn't fill. I checked in the loft and found that the ballcock in to the F&E tank had stuck with the float in fresh air as the water had entered the system.