Central Heating Woes!

[Mean Al]

Hello All

I've been having fun with my old vented, Y-Plan central heating system, since I finally got it up and running again yesterday, having had the system out of service since around March. The system was in a bad way, with rusty radiators, a noisy pump, and generally poor performance. Actually, when I say a 'noisy pump' it sounded like a jet engine taking off, and this sound reverberated throughout the house!

So I fitted three new radiators, a new pump, a new mid-position diverter valve and a new cylinder 'stat to the system. The new pump is a Grundfos UPS3 and the mid-position valve is the standard Honeywell V4073A guy. I'm confident that the pump is facing the right way, and that the 3-port valve is set up correctly.

So with the latest cold snap, I finally pulled my finger out to complete the works and get the system up and running. Here's where the real fun started...

The system filled up fine, and I took the opportunity to add Sentinel X400 inhibitor as it was filling. The boiler started without difficulty, and I was able to bleed every radiator and obtain heat from all the rads (eventually).

The problem that I now face is that the system now pumps over into the F&E tank. The rate of pumping over varies, but even on pump setting '1', there remains a steady trickle of hot water streaming from the vent pipe.

During my efforts, I noticed that there is an air separator in the airing cupboard, and I suspect that this is full of gunge, as a magnet will stick to it. The problem is that the position of the air separator is a real pain to get to, and I really don't want to go cutting it out if I can possibly avoid it. I've also seen that an isolation valve was fitted to the cold feed right next to this separator - I actually replaced this too, although I have since learned that the practice of fitting such a valve to the cold feed is frowned upon.

My plan is to drain the system, remove the service valve on the feed pipe, and 'rod' the air separator via this pipe (it is literally just a few inches away). What are my chances of this solving the problem?

If indeed this clears the blockage and solves the pumping-over issue, then should I remove this isolation valve and replace it with a simple straight coupler? I can see that this valve would be useful when it came to replacing radiator valves in the future, but I don't want to leave something fitted that breaks any byelaws.

In the meantime, I am pumping the X400 cleaner round the system, which otherwise performs perfectly. It's just a pity that the circulation all seems to be going via the expansion tank, which is slowly turning my loft into a sauna, and probably eating away at my new radiators!!

Any suggestions for how to deal with the situation would be very much welcomed.

Regards,

Alan.

 

[exedon2]

Picture of what you have would be most useful
Have to say as you have to drain down getting shut of air separator would my priority and use a close coupled pipework solution.

 

[Last Plumber]

Some air separators where made of steel with copper tails.
I would doubt very much that your plan will solve the issue but you never know your luck.
Best idea is as above, more info, some photographs would help us to help you.

When I see those devices I always have dark thoughts. I never saw the point in them personally as it is just as easy to pipe a system correctly without the gadgets. That is my opinion of course and I expect others will disagree with it. I look at them as an attempted solution to a bad job or a method used by builders plumbers during site work/new builds.

 

[Mean Al]

Hello All

I've been having fun with my old vented, Y-Plan central heating system, since I finally got it up and running again yesterday, having had the system out of service since around March. The system was in a bad way, with rusty radiators, a noisy pump, and generally poor performance. Actually, when I say a 'noisy pump' it sounded like a jet engine taking off, and this sound reverberated throughout the house!

So I fitted three new radiators, a new pump, a new mid-position diverter valve and a new cylinder 'stat to the system. The new pump is a Grundfos UPS3 and the mid-position valve is the standard Honeywell V4073A guy. I'm confident that the pump is facing the right way, and that the 3-port valve is set up correctly.

So with the latest cold snap, I finally pulled my finger out to complete the works and get the system up and running. Here's where the real fun started...

The system filled up fine, and I took the opportunity to add Sentinel X400 inhibitor as it was filling. The boiler started without difficulty, and I was able to bleed every radiator and obtain heat from all the rads (eventually).

The problem that I now face is that the system now pumps over into the F&E tank. The rate of pumping over varies, but even on pump setting '1', there remains a steady trickle of hot water streaming from the vent pipe.

During my efforts, I noticed that there is an air separator in the airing cupboard, and I suspect that this is full of gunge, as a magnet will stick to it. The problem is that the position of the air separator is a real pain to get to, and I really don't want to go cutting it out if I can possibly avoid it. I've also seen that an isolation valve was fitted to the cold feed right next to this separator - I actually replaced this too, although I have since learned that the practice of fitting such a valve to the cold feed is frowned upon.

My plan is to drain the system, remove the service valve on the feed pipe, and 'rod' the air separator via this pipe (it is literally just a few inches away). What are my chances of this solving the problem?

If indeed this clears the blockage and solves the pumping-over issue, then should I remove this isolation valve and replace it with a simple straight coupler? I can see that this valve would be useful when it came to replacing radiator valves in the future, but I don't want to leave something fitted that breaks any byelaws.

In the meantime, I am pumping the X400 cleaner round the system, which otherwise performs perfectly. It's just a pity that the circulation all seems to be going via the expansion tank, which is slowly turning my loft into a sauna, and probably eating away at my new radiators!!

Any suggestions for how to deal with the situation would be very much welcomed.

Regards,

Alan.

 

[Mean Al]

Pictures now added, as requested. The first image shows the full extent of my plumbing efforts! The second image shows the air seperator (which I suspect is the cause of all my troubles), together with the dodgily-positioned isolation valve. My plan was to remove this valve and rod the crap out of the air separator!

 

[SJB060685]

Looks like pump is pumping wrong way?

 

[Mean Al]

Looks like pump is pumping wrong way?

Hi SJB. Pump is definitely pumping the correct way. Prior to fitting, I turned the control head around (through 180 degrees), so that it faces the right way up. The arrow on the body of the pump points down however, towards the 3 port valve. Good spot, though!

 

[SJB060685]

A logical man, well done! You're right that copper cannot be magnetised and if this is actually a copper separator then the magnet sticking is a sign of black iron oxide (sludge). The problem is the unit is painted. When you placed a magnet to it did it stick to it at all points, or just one?
Based on your explanation of what condition the system used to be in im pretty confident the problem is in that area too, although I've been wrong many times .
There's no problem with an isolation valve on the cold feed, how else would you isolate without climbing in the roof? The vent however should never be compromised.

 

[exedon2]

Should be easy enough to turn that into a H section open vent cold feed just keep section between tees less than 150mm
Certainly would not try to clear air separator dreadful things and every chance of putting big lumps of crap into system.

 

[John.g]

The UPS3 is a pretty powerful pump even on fixed speed1 where it is still a 4.2M pump up to nearly a flow rate of 13 LPM so will show up any "frailties" in a open vent system.
I would suggest changing to constant pressure CP1 setting which is a constant 3M head and may well stop that dribbling or try proportional pressure PP2 which may work even better in helping to prevent venting over and still give sufficient flow.

 

[SimonG]

And get rid of that crappy valve on the cold feed. It's not rated for central heating and is just waiting for an invite to leak.

 

[Mean Al]

A logical man, well done! You're right that copper cannot be magnetised and if this is actually a copper separator then the magnet sticking is a sign of black iron oxide (sludge). The problem is the unit is painted. When you placed a magnet to it did it stick to it at all points, or just one?
Based on your explanation of what condition the system used to be in im pretty confident the problem is in that area too, although I've been wrong many times .
There's no problem with an isolation valve on the cold feed, how else would you isolate without climbing in the roof? The vent however should never be compromised.

The magnet sticks to the entire body of the air separator. It would be great if it transpired that it was indeed made of steel. Regarding the isolation valve, my original plan was to keep it there, if for nothing else but to make future servicing easier. I also thought to replace it with one of the 'full bore' variety. Apparently though, that still contravenes some rules. I realise that, as you say, the critical path is the vent, which should never be obstructed or compromised in any way.

The reason that I'm so reluctant to cut out the air separator is that I just know it will be a pig of a job, hence my idea to try and clear it by any means possible first!

Alan.

 

[Mean Al]

The UPS3 is a pretty powerful pump even on fixed speed1 where it is still a 4.2M pump up to nearly a flow rate of 13 LPM so will show up any "frailties" in a open vent system.
I would suggest changing to constant pressure CP1 setting which is a constant 3M head and may well stop that dribbling or try proportional pressure PP2 which may work even better in helping to prevent venting over and still give sufficient flow.

Hi John,

Many thanks for the suggestions. You are right - so far I have only tested the new UPS3 with the three 'constant speed' setttings 1, 2 and 3. I will experiment with the constant pressure and proportional pressure settings next, and let you know the results!

By the way, the UPS3 is a groovy-looking pump, especially with its row of LED indicators! Definitely my favourite part of the new system. Seems almost a shame to keep it hidden away from view!

 

[Gasmk1]

The air separator looks as though all copper I presume the 15 mm feed is the cold feed i think you will find the separator will be full of magnetite

 

[Last Plumber]

Hi John,

Many thanks for the suggestions. You are right - so far I have only tested the new UPS3 with the three 'constant speed' setttings 1, 2 and 3. I will experiment with the constant pressure and proportional pressure settings next, and let you know the results!

By the way, the UPS3 is a groovy-looking pump, especially with its row of LED indicators! Definitely my favourite part of the new system. Seems almost a shame to keep it hidden away from view!

When the heating/hot water is running, close the by-pass (if it is open) and see if the trickle stops. I would replace that with a 22mm auto by-pass anyway (piped 22mm).
How far open is the cylinder return valve?
I would check these things along with pump speeds first, before going onto suspected blockages.

 

[Mean Al]

Should be easy enough to turn that into a H section open vent cold feed just keep section between tees less than 150mm
Certainly would not try to clear air separator dreadful things and every chance of putting big lumps of crap into system.

Thanks Exedon. If I go ahead and cut out the air separator, then I may well replace it with a standard 'H' section, as you suggest. I'm really hoping that I can somehow unblock it as a short-term measure, though!

 

[exedon2]

Once you have drained it down pipework is dead easy
First drop pump about 150mm (have to reposition clip) tee for cold feed tight above it short end 22mm across to flow equal tee cut in . Cut expansion just above air separator maybe a elbow and a m&f job done . I would use tectite fittings quick and no hot work.

 

[Mean Al]

The magnet sticks to the entire body of the air separator. It would be great if it transpired that it was indeed made of steel. Regarding the isolation valve, my original plan was to keep it there, if for nothing else but to make future servicing easier. I also thought to replace it with one of the 'full bore' variety. Apparently though, that still contravenes some rules. I realise that, as you say, the critical path is the vent, which should never be obstructed or compromised in any way.

The reason that I'm so reluctant to cut out the air separator is that I just know it will be a pig of a job, hence my idea to try and clear it by any means possible first!

Alan.

Thanks to everyone who offered suggestions as to how to fix my problem. I wanted to let anyone who was interested know the outcome, and how I finally solved my central heating woes!

The pumping-over rapidly became an emergency, as the heat from the water in the header tank caused the ball float to fail, and it subsequently filled with water and sank. The next thing I knew, I had water pouring out of the overflow pipe in the eaves - thankfully it did its job and saved me from disaster!

In a panic, I switched off the water mains to the tank, shut the boiler down and drained the system whilst still hot (having run Sentinel X400 through it for a week). Once empty, I bailed out the remaining water from the F&E tank, removed the isolating valve on the cold feed, and rodded the crap out of the air separator with a straightened wire coathanger. Lots of black sludge came out of it, exactly as I expected. When I was draining the system, I made up a hose with a clear section so that I could see what was coming out of it - see photo. The water looked like coffee! I understand that this means my system is suffering from corrosion.

Removal of the valve left a gap in the feed pipe too wide to install a standard compression coupling. So I did the next best thing, and replaced it with a full-bore valve, which was just a bit longer, and so required cutting out 1cm of pipe from the cold feed. So I still have a valve on the cold feed, but at least it is now a full-bore version, which shouldn't impede flow, and might be more suitable for working on a central heating system. Needless to say that the 22mm vent pipe remains uncompromised.

I then replaced the ball float in the F&E tank, filled the system back up again, added another bottle of X400 system restorer, and 'voila!' - hot radiators with NO pumping over! I could feel the horizontal section of pipe from the air separator to the pump getting red hot, where previously this section of pipe remained cold, as the water all went up the vent pipe towards the tank, and then back down the feed pipe.

Even setting the UPS3 to position '2' did not result in any pumping over, so I'm hopeful that the system will remain stable for a good while. I realise that, in the long term, I should still replace the air separator, but I suspect that if I run the Sentinel X400 for a few weeks, then dump it whilst it is hot, I will probably get rid of most of the sludge.

Anyway, I just wanted to let all that helped with my question know the outcome. I might try the pump on setting 3 later, just to see what happens!