Potterton Suprima system - tripping out - help please!

S

sai_2

Hi,
I have a central heating system that has been causing me no end of problems. It was installed 5 years ago. A new Potterton Suprima 30, four new radiators and a hot water cylinder.

The cylinder is connected up like a radiator using a tapstat, so that when the water in there is hot, it closes the valve and there is return pipe that sends the water back, bypassing the cylinder completely.

Original problem
It took 3-4 hours or more to heat up a cylinder of water (big problem) and the rads weren't getting hot enough. Occasionally the boiler tripped out, so that you were guaranteed a lovely cold shower in the morning :)

Solution
Automatic air-release type valve fitted to the cylinder. That seemed to fix the 3-4 hour problem. Full cylinder of water now in just 45 minutes.

Rad problem
So the rads weren't all getting hot enough still. Each one was evenly hot (i.e. no cold spots at top or bottom), but not hot enough to burn your hand.

Occasionally, they did get super hot, but this was a rare thing.

The first one of the four rads in the series was normally the most consistent in terms of heat. This is a large towel-radiator in the bath room. I did expiriment with turning that one down a bit and this seemed to help balance the system somewhat, but it was still quite rare for all of them to get hot as the boiler never burned for long enough. It comes on, heats some water an then flashes green for a few minutes before burning some more. Occasionally, it would trip out, but this was quite rare, e.g. once a month or so.

Anyway, it started tripping out more frequently, so BG came round and turned the pump up to 3 (it was on 2 before). The engineer didn't check the PCB, so I don't know if this is at fault.

Immersion element
This was installed along with a new cylinder. The old cylinder didn't have an element and the slot couldn't be freed up, so a new cylinder was installed. The system was drained down (water was clean), cylinder and immersion fitted and refilled. Immersion checked and working great.

However, now there were some strange scraping noises coming from some of the pipes when the boiler came on (after a couple of minutes), followed by a pretty scary series of banging sounds, followed by the boiler cutting off (all within a few minutes). I did notice that there was some air in the system, which I managed to bleed from the rads, but this didn't help.

BG came round and installed a new pump. Apparently, the old one had failed. They installed a BG branded one and it has been left on 3. Now nothing works. The boiler comes on for about a minute and then goes off. After a few goes, it trips out and needs a reset. One of the pipes from the boiler is very hot at this stage and the other one is cool. There are no banging or scraping noises at all now. The pump sounds like it is doing its job.

That is pretty much where I am now. BG came around again and said that there is no circulation at all and the system needs a flush due to sludge. Does that sound correct? Or is the problem with the Potterton? Any suggestions would be very welcomed.

I did wonder if there could be sludge in the system if only 3 weeks ago, the whole system was drained and the water was clean? I did speak to the plumber that did that job and he has 30 years' experience and he thinks that sludge is definitely not an issue. Also, the rads have never had cold spots at the bottoms (very occasionally at the top due to air though).

A few other things that may be relevant:
There is no room thermostat anywhere. The rads each have a thermostatic control on them (except the first one).
Because of the way that the system is set up, the timer only used the "heating advance" side. The "hot water advance" is redundant. So if you want hot water and no heating, you just turn the rads off. Silly I know, but it seems to work, when it works.

Thanks in advance.[/b]
 
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just cos the motor is running dosent mean the pump is pumping

you have undone the screw in the middle and made sure the motor is turning
 
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sounds like an air lock to be honest....is there a bleed point in the pipework?. Also are we loking at an s plan system ie 2 x 2 port valves?.....if so make sure the bypass valve is open as the suprima will run the pump after demand has ended and valves closed.
 
S

sai_2

Thanks for the replies. I will check the pump tonight.

I have also asked BG to send another engineer out for a second opinion - he is due on Friday, so I will pass on your comments and see what he says.

Thanks again.
 
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S

sai_2

I went and had a closer look at the system tonight. Here is some more detail.

The pump is a brand new British/Scottish Gas branded Grunfos Mulithead G. I took out the central screw and a bit of water came out. I advanced the timer and it started whirring away. A little bit of water came out, but not loads (a few drops at a time). Anyway, the pump was definitely whirring away nicely.

I then checked to see what is getting hot and what is not. Here is what I found. The pipe that is going through the pump is cold, so I guess this is pumping back into the boiler. Is that correct?

The pipe that is getting hot when the boiler fires up is not connected to the pump directly. So it goes:

Boiler - rad 1 - rad 2 - rad3 - rad 4 - return pipe - pump - back to boiler.

Is that correct?

Anyway, it seemed better todar. The pipes to the rads were getting hot. Really hot at rad 1 and warm at rad 4. The return pipe was cool and so were the rads (although this was only after 10 minutes!)

The pipe to the cylinder was also nicely hot (cylinder connected vie tapstat valve, i.e. more or less like a rad)

I will let you know what the BG engineer says tomorrow.

Thanks.

ps Ollski, thanks for your answer, but I don't know where to find the bleed valve or what the S system means..?! I will pass your comments on to the engineer though. If you can give me more detail, I will check myself.
 
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sai_2 said:
I will pass your comments on to the engineer though.

sai I wouldn't bother doing that mate, it's very rarely appreciated!
 
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Beg to differ but some of the B G elite engineers may appriciate some constructive comments :evil:
 
S

sai_2

OK - its fixed! And what a great boiler it is when it is working like it is now.

I'm not sure what the BG engineer did as I missed him. But he certainly didn't flush the system in 1 hour and with no payment! :rolleyes:

So I am guessing it was an air lock as Ollski suggested (nice one!)

All the rads get nicely hot and there is pleny of hot water within 45 minutes.

The boiler buns happily for 15-20 minutes, stops for about a minute and then carries on - like clockwork. The pump carries on during the break periods.

Two of the rads have some air in them, but I can sort that out.

Bleed valve - there are two pipes at the top of the boiler. One pipe goes into the boiler at a 90 degree angle straight down, but the horizontal section carries on also for a few more inches. At the end of that there is some kind of valve. Just for reference, is this the bleed valve and how is it used if so?

Thanks a lot. :D
 
S

sai_2

Spoke too soon. Went back today and found a new set of problems :(

I also spoke to BG and apparently, the engineer never made it round on Friday. It was just coincidence that it was working for those few hours I guess. An engineer is calling tomorrow.

The cylinder was full of hot water. The rads were all stone cold. The timer is set to twice daily (about 2-3 hours am and 2-3 hours pm) to keep it ticking over.

I found lots of air in two of the rads. None in the other two.

The new pump sounds like it is "out of breath". It is whirring away when the boiler kicks in but is making a regular noise like it is in pain! The noise increases/decreases as the pump is switched up/down.

The boiler kicks in for a minute or two and then switches off. The pipe leaving the boiler is super hot. The pipe from the pump back to the boiler is cool.

When I aired the rads, the water was very clean.

Has the air-lock moved around.. is that what has happened? If that is the case, can someone help me locate the bleed valve? From my previous post, is this it and how do I use it?! :eek:

There are two pipes at the top of the boiler. One pipe goes into the boiler after a 90 degree turn straight down and the horizontal section carries on also for a few more inches. At the end of that there is some kind of valve.

Thanks! :D
 
S

sai_2

I think I found something useful. I think my system set up is a "Home Warm" system?!

"This system was a low cost version of the Y Plan, except a Primatic cylinder is used and the pump is on the return. (Using a Primatic cylinder is not recommended on a fully pumped system)."

Does that help? :confused:

My pump is sending water back to the boiler, rather than pumping it away from the boiler.
Other clues: there is no 3-way valve (as far as I know), there is no room thermostat and boy, this is getting depressing.. do I need a whole new system? :(

http://www.gasman.fsbusiness.co.uk/images/hwm.gif
 
S

sai_2

Do you bleed the pump by loosening the big round screw? Also do you do this with the system on/off cool/hot?

Thanks.
 

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