Potterton Profile 80e keeps shutting down

[Moorf]

Hello everyone!

I have a conventional open vented system with a Potterton Profile 80e situated in the airing cupboard next to the hot water cylinder, with a feed and expansion tank in the loft. The house is a bungalow with 9 radiators, although one rad is in a basement room.

For a while now there has been air present in the system, yet none comes out when I bleed the rads. There is a automatic air vent above the boiler on the return feed and as said it's an open vented system, so surely this air should find it's way out via the vents?

In recent days the sound of air got worse to the point that it glugs and gurgles around the boiler and hot water tank and the boiler shuts down. I've drained the system and refilled and now it seems quieter when on heating only but it still gurgles when on heating and hot water.

Despite what mode the boiler is on it starts and runs for a couple of minutes then shuts down for a couple of minutes then starts up again. The pump appears to be OK as all the rads get hot.

I'm wondering if I have 2 separate issues here, with the air in the system and the boiler shutting down or if it's all related. Sorry for the long winded explanation, but hopefully I can get some pointers as to what is happening.

Many Thanks!!

 

[JohnD]

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

When you drained and filled it, did you use a cleaning chemical?

 

[Moorf]

Yes all the radiators bleed normally, although as it's a bungalow all the rads are on the same level apart from one in the basement and yes I put a cleaning chemical in when I refilled it.

 

[Moorf]

I'm really puzzled by this. How in an open vented system can air get in? and why is it not venting out via the F/E tank?

Although I'm not an expert and I might be wrong, my feeling is that the boiler is OK as it runs fine for about 20 minutes and then air starts glugging and the boiler shuts down for a bit and then starts up again. So air is getting in somehow.....

As I've got an automatic air vent on the CH return pipe, is it worth plugging the vent over the F/E tank to see if its sucking in air there?

 

[picasso]

Had a new pump fitted recently ?

 

[Moorf]

No, but had new 3 way valve about 3 years ago.

 

[muggles]

Thought you had a GlowWorm Betacom? Do you have two houses?

 

[Gas2Air]

Partially blocked cold feed. Are the open vent and cold feed fitted after the pump? What speed is the pump on? Yes you can try to see if the vent is sucking in by having the system on and using a cup full of water around the vent. You could have a small leak somewhere sucking air in.

 

[Moorf]

It has a combined feed vent (Y plan?) and I did wonder about a blockage but it drained down and refilled without any issues....

The feed/vent pipe is tee'd just after the outlet from the boiler and before the pump and I can't see what speed the pump is on as it's tucked behind the cylinder somewhat, but it hasn't been tinkered with.

I'll try the glass of water trick! Thanks!

And yes I also have a Glow Worm Betacom which is in a rental.

 

[Moorf]

So I've run the system this evening with the vent pipe over the F/E tank in a glass of water and all that happens is that the water level goes up and down a few millimeters.

I'd discounted a blockage in the cold feed pipe as it drained down and filled up again, but I may have another look at this tomorrow. It didn't drain down very fast as the washer on the draincock stuck, but I've fitted a new washer now so I'll be able to see how fast it drains down with the drain cock fully open.

I was wondering about filling the system from a hose attached to the draincock (secured with a jubilee clip) to see if I can dislodge any crud. Sort of back flush it?

 

[picasso]

Can you bleed the pump ?

 

[Moorf]

Yes. I ran it for a while last night with the bleed screw off and some air came out, but mostly water dribbling out.

 

[JohnD]

if you are draining and refilling, consider adding a litre of Sentinel X400 on the refill. It is a mild chemical cleaner (not an inhibiter) and loosens sludge and sediment. It may be that you have a hard blockage that needs physical removal, but X400 is cheap and easy and will do nothing but good. It is about £15 and you can leave it circulating for about four weeks before draining out.

Have you got a magnet?

 

[Moorf]

Will a fridge magnet do?

I put a bottle of Primaflow cleaner in when I refilled it on Friday, but I'll get a bottle of Sentinel tomorrow for when I refill again.

 

[Moorf]

I've had another go at this today.

Firstly I went along the feed/vent pipe with a magnet and found nothing. Then I drained the system and it drained down quickly and there was good pressure coming out of the hose. After that I untied the ballcock and let it flow through the system for a while and again there was good flow of clean water coming from all 3 draincocks. So I don't think I have a blockage.

I refilled, bled the system, including the pump and switched on. The pump made a horrible noise at first like the bearings are going, but settled down after while and is now nice and quiet again. I assume that I hadn't got all the air out? One thing I did notice when the system was filling was that there was water spitting out of the automatic vent. Is this normal?

Anyway again after about 10 minutes there's air glugging and gurgling again and the boiler shuts down. So I switched the boiler off and left the pump running for about half an hour and everything's running nice and quiet. I switched the pump off, left it for a while, bled the system again and then turned it all back on. Within 10-15 minutes it's glugging and gurgling again!

So I've done this a couple of times now and it only glugs and gurgles when the boiler is running. If the boiler is turned off with the pump left running it is nice and quiet. The only thing I can think of now is that the automatic vent is sucking in air, and it's collecting in the heat exchanger until it glugs out into the flow pipe. But why does it do it only when the boiler is operating?

The other possibility I guess is that air is getting into the heat exchanger or through a connection somewhere in the boiler? but there arn't any leaks!

Very confused!