Air and pumping over

[teejay246]

Hi
I am a newbie here so here goes:
I have an open vented system 30 years old. Old house mix of old cast iron rads and newer ones- 18 in all. The system is divided by two zone valves into 1. Downstairs Bathroom, office, living room and hall 2. 2 bedrooms plus 3 public rooms downstairs and 2 upstairs plus upstairs bathroom. With circuit 1 ON and 2 OFF, system was sucking air from somewhere.
Pump ( new Grundfos 15/60 ) noisy with air. I bleed the air manually from the pipe at the top of the system - all goes quiet for a couple of hours. I put on both circuits 1 & 2 and all is quiet for hours but eventually the noise at the pump. Also from time to time I get overflow from balance tank in loft.

( Its a bungalow so loft is on same level as the bedrooms upstairs thus very little "head". Big old hot water storage tank, secondary hot tank with immersion heater, cold water storage to feed hot tank and CH balance tank mounted high as poss under rafters. All worked fine for 29years after piping down to 8mm from 2" and new boiler 1983
Boiler is an ideal Mex 26kw located in a downstairs utility / shower room. Top Flue through roof 4mtrs.

I know that the sytem has a fair amount of sludge and also black deposits ( seen on valves and pipe ends ) so last weekend I decided to put 2ltrs X800 in the system and run the system for 4 hours ( this after taking advice from Sentinel to run for 1 hour or up to a few days...and also reading many posts in favour of X800 left in for a few hours even without the power flush bit.)
Well after four hours - whole system running at normal temp. during which system is quiet as a mouse and running beautifully - no over pumping no pump noise....I drained down the system as per normal procedures etc. Disappointed that the outflow wasn't a really dirty sludgy colour....looked pretty clean- just a beige soapy stream and no sedimentary deposit left by the grid/drain either. So, fitted a brand new auto trickle air vent at top of system ( Italian float type - nice looking piece of kit )- the old bleed valve was clearly sludged up and quite rotten.... re-filled the system, added inhibitor, bled all the rads lowest first etc.and off we went.

With circuit 1 ON and 2 OFF, pump started to get noisy again, clicking in one of the rads ( air ) so sucking air from somewhere such that the trickle vent does not cope. Pump ( new Grundfos 15/60 last year ) noisy with air. I bleed the air manually from the pipe at the top of the system - all goes quiet for a couple of hours. I put on both circuits 1 & 2 and all is quiet for hours but eventually the noise at the pump ( which was installed on the RETURN all those years ago ) starts up again requiring me to manually vent again. ALSO for a long time been getting overflow from the balance tank in the loft. No contamination at all in the hot water, no discolouration, no taste, smell etc.( separate system but thinking of a coil issue if it has a coil - suspect its direct though - unless the small immerser tank DOES have a coil).
Is it the amount of sludge/crud in the system?? I have now bought 3 ltrs of X400 with the intention of starting again - leaving the X400 in the system for about 3-4 weeks??
Ideas/ suggestions please.
Many thanks

 

[Simon F]

Hello Teejay:welcome: are you sure you've not missed anything ?:rolleyes2:
did the problem only start after the new pump was fitted?
what speed is it set to? was it moved?
if so might be a pipe work issue, other wise like you think probably a blockage
what height is the overflow pipe above the f+e tank?

 

[teejay246]

Hello Teejay:welcome: are you sure you've not missed anything ?:rolleyes2:did the problem only start after the new pump was fitted? what speed is it set to? was it moved? if so might be a pipe work issue, other wise like you think probably a blockagewhat height is the overflow pipe above the f+e tank?

OK. I am a stickler for facts :icon11: Reckoned it might save too many Qs.
1. When old pump started being noisy, decided we needed a new one. Plumber fitted the new one, the modern version of the old one. Problems started then.
2. Plumber said it was probably that the new pump was more efficient and stronger.
3. Another plumber I called said - too much crud in the system.
4. another one said it was because the pump was on the "return"....bla, bla....
5. Pump is set at 1 all the time...but when I was circulating the X800 I set it to 2. and no probs at all with whole system running.
Sorry for my ignorance but what's the F=e tank? The overflow pipe is connected to just above the set water line on the balance / feeder tank which has a toilet cistern type ball and valve.It's always been set up this way and no probs. Not sure about the blockage, System seemed to drain and fill OK. All rads heat up OK.Thanks:uhoh2:

 

[dancinplumba]

hi and welcome, f+e is what you call 'balance tank'
30 yrs, time to modernise perhaps ? with something more efficient 🙂

 

[Brendan Rodgers]

Sounds like a blockeage in something not allowing the system to breath, therfore pumping over.
Have you got a bypass/set correctly?
Dose it refill quickly, possable blocked cold feed, How much head have you between water level in expansion tank and highest point of horizontal pipework?
If you cant find the blockage, fit a presure set to it but dont run above 1bar.., expansion vessel, safty valve and gauge, size depends on volume of water in system..

Bren.

 

[teejay246]

Sounds like a blockeage in something not allowing the system to breath, therfore pumping over.
Have you got a bypass/set correctly?
Dose it refill quickly, possable blocked cold feed, How much head have you between water level in expansion tank and highest point of horizontal pipework?
If you cant find the blockage, fit a presure set to it but dont run above 1bar.., expansion vessel, safty valve and gauge, size depends on volume of water in system..

Bren.

Thanks Bren
Well, not sure what is meant by "bypass". Do you mean what I call the auto air bleed.
If so, its a little chrome screw-in device with a membrane of some sort and a screw top. When there is air, the membrane dries out allowing air to escape. As soon as water hits the membrane it swells and shuts off the water. I am pretty sure this new one I fitted isn't working as it should. The screw when loose goes tight again when continuing to unscrew whilst another one I have on a downstairs rad works beautifully. Unscrews easy and lets water flow and when just finger tight it seals ok. Never get air in that rad either. On the one in the loft, I keep having to tweak the screw up and down and then I get the air out. If I open it too much it does not shut off the water. That I bought the float chamber version but had my doubts this was doing its job. If I keep doing it manually system is happier.
This device is on the end of an upright 12 inch section of 15mm pipe that is connected by a tee to a horizontal CH pipe pipe below it. See photo.
The F&E tank bottom is 2ft above the highest horizontal CH pipe.
The system refilled quickly enough and all rads heat OK.
The cold feed to the F+E is no probs.
There is some crud on the bottom of the F+E tank too.
What about the X400 idea for a week or two then drain and let the feed run for a while to wash out the system???:20:

 

[diamondgas]

teejay246 🙂

sounds like you've done yourself some research or know a bit or too?

You mention 2 zones. How is your hot water heated?

However with what you've described I'd be enclined to recommend a proffesional in. To me it sounds like you have potential pumping over/surging issues that over the years may have compromised the circulation?

GOOD NEWS is that 30yrs is a good life for a heating system 🙂

 

[Brendan Rodgers]

If you got zone valves on the system you should have a bypass between the flow and return after the pump before valves.
also fit an auto air vent and that will release any trapped air automatically as you said it runs better after been bled. The bypass could not be open enough, if not shure mate get a pro in as you could end up doing more damage if you mess with the wrong valves.
good luck mate.
p.s., yes thats just a manual vent on the pic, for refilling and venting.

 

[teejay246]

Thanks everyone
Re the pros. I have had so many bad/negative experiences over the last two years, from local guys all Corgi reg, all giving me a different story, giving conflicting opinions, and all wanting to sell me something I have no idea who to believe or who I can trust. So far I have done better by taking advice such as here on this forum

Yep Bren, 2 zone valves both on the "flow" adjacent to the boiler. The pump is on the return again adjacent to the boiler. What about this auto vent I bought. See pic. Haven't tried it properly yet. It will replace the manual one you saw. I cannot see any kind of relief valve near the boiler though :blush5:

 

[teejay246]

Sorry, I forgot to answer your question. The water is heated together with the CH or alone. It's a complicated setup ( for me anyhow ) There are two tanks. 1. the original big copper tank which is where the volume of hot water comes from and 2. a smaller more modern-looking tank with an immersion heater in it and which, when only the immersion heater is used is woefully inadequate for the vol we need. On the top of this smaller tank there is a really weird connical device with a lever secured with a padlock. It is a release valve of some kind! see picture. BTW with just the hot water on the pump is intermittently noisy like with CH on.

.

 

[secret squirrel]

I don't understand why people will replace a perfectly good car after 5 years because the 'fancy' something different but refuse to get rid of a severely problematic heating system with probably more than one fault that is 30 years old!

Trouble is for any professional looking at this system you cure one issue to hit another, its not that the engineer is incorrect he's dealing with 30 YEARS of probable neglect, corrosion and worn parts.

To make matters even more drawn out and painful the customer doesn't trust the advice of a professional looking at the problem first hand! Oh I've had a bad experience.

Just because a customer can put X800 in a system doesn't make them an expert, I can change the oil on my van but I can't give it an MOT.

Sorry, just getting over the flu! and clearing a blockage.

 

[Brendan Rodgers]

That is a safty valve, dont touch it, if you try to release it chances are it wont re-seat.
The Auto air vent is perfect, replace the manual one and that will vent the system for you whilst its running. Ther should be a by-pass somewere, a short bit of pipe linking the flow and return with a valve on it, make sure that its open at least 4-5 turns anticlokwise...that should be after the pump, before the zone valves..if you havnt got one then this could be wye its problematic....

Bren.

 

[teejay246]

I had no intention of coming across across as an amateur expert. I merely tried to give as much info as possible to help someone to help me. Maybe there is no recession in the plumbing business and if that's the case "great". Some of us don't have just three grand to replace a system, quite yet and when we do we want to be very sure we have a tradesman who will fit what is needed rather than what they want to sell 'em or what's "easiest for them! ( sorry but this has been my experience last year - quoted by by three corgi pros who all told me what was best and every one was entirely different. Not to mention one who really did not want to spend time looking at how my system was configured in the first place - just wanted to strip everything out and start again.)
This system is not neglected. It gets drained down and flushed every couple of years.Yes there's corrosion in there. It's been working just fine. There are brand new rads on the system, thermostatic valves and yes old cast iron rads the ones that are much in demand ( antiques they may be but they give out a great heat ) The only moving parts are the motorised valves, the pump and the boiler. The pump is new, the m.valves may need looking at and the boiler works fine.
I am looking for some guidance not a "lecture". Thanks

 

[Brendan Rodgers]

i think the squirrel,s having a bad day, run out of nuts maybe..a tad negative and not very helpfull, thought thats Wye we are here

 

[teejay246]

Thanks for that. It's an "air" issue. No over-pumping the last few days. I changed the auto air valve to the float type last night. System seems to be pushing the air around. Sometimes pump is totally silent for an hour or so, then starts noise for a few minutes then quiet again. It's still noisy with just the HW on I've noticed but probably air in the pump and I am loathe to keep bleeding the pump as I think I have to screw it a bit tighter now to prevent drip.

 

[dontknowitall]

Sounds to me that there is a missed vent somewhere in the system (not the auto vent you've found, but another one - a manual vent). Is the pump bled? Are all the radiators bled of air? When the system is bled, has it been done so with the motorised valves open? These can stop air escaping when closed. Is the F&E cistern (the small one in the loft) totally clear of crud?

If the answer is "Yes" to all these, then on this forum we're in the tricky position that we cannot see how the pipework is laid out in your house and, therefore, where it might be worth looking for potential areas for investigation.

To give some examples, I bled the air from a heating system a couple of days ago. The bleed valve was about 10 feet up in the airing cupboard, hidden in the corner. Another house I've been to has two bleed valves in the loft as well as another on the first floor. Other houses don't have a bleed valve and rely on the heated towel rail to collect the air in the system.

If the system is drained down and flushed every two years (why?) then can you find the plumber who did this, as he'll have probably come across this problem when re-filling the system?

Re the vehicles, my van is going in for a service, repairs and MoT next Monday and Tuesday and I'm expecting a bill for £500-£600. Nothing major for cars/vans but if only some of us plumbers could be on those wages ...

 

[Nostrum]

Fitting an auto air vent is not the answer to the problem. Air inside your system is what will cause the sludge etc, so you need to resolve that first and foremost. Generally there is only 1 place the air can enter, and thats the expansion/vent pipe dangling over the F+E tank. When you say you have fitted new radiators, have you fitted any tall type or towel rails to the upstairs?

I think someone already asked you, what is the distance from the highest point of your heating system to the water level in the tank? Have you got pipework in the loft? Is there room to move the F+E tank up higher if required?

Some pictures of the set up (pump motorised valves etc) would speak 1000 words and also some idea of how it is all configured. It's really hard to give a definitive answer on these issues from a distance, but I don't see why you should be ripping it all out, it could be something fairly simple albeit not an overly efficient system. Where about's are you?

 

[Brendan Rodgers]

Sambotc, seems to be ok with the head as iv asked that, but Teejay, how much distance do you have between the open vent highes point, and the water level in the f and e tank?
And yes, as above Teejay, some clear pics mate would help Masivley...

 

[teejay246]

Sambotc, seems to be ok with the head as iv asked that, but Teejay, how much distance do you have between the open vent highes point, and the water level in the f and e tank?
And yes, as above Teejay, some clear pics mate would help Masivley...

Thanks guys for all your help on this. Here are some pictures were okay and that you can read the comments.
Observations today
You will remember I mentioned that I had fitted a new float chamber type auto air vent. It didn't appear to work at all. I spoke to the manufacturers and they showed me how to take it apart to check everything was all okay and it was.
This fancy new assembly comes into parts one of which is check valve which allowed it to remove the main part of the float chamber for servicing replacement etc. The whole assembly is about 4 inches tall. I could tell there was evidence system because pipe to the air vent went cold from halfway up -- so why wasn't the float chamber releasing the air?
When I started to on do it from the check valve and before the check valve cut in, I could get the air out until the water showed up. Then the pipe would be hot for an hour or so the gradually start going cold again. Bizarre!
I got the idea to take off the check valve and without it. Lowering the assembly by about an inch hey presto! The chamber started to work on its own releasing air - not a lot but at least it showed it worked.
Q. could I be right in thinking that the new height of the air vent pipe is causing a problem. Remember the old vent valve was seized so it wasn't letting any air out either.
NEXT
with the motorised valves and the system I went round checking the air in the radiators. I found anywhere in the radiators upstairs (same level as the space) so I released that. I started the system backup but just put on the hot water. All nice and quiet for about half an hour then the pump started getting noisy with air again.
I put on the big zone, the one with 11 radiators on it for about 10 minutes and the system went quiet again. Then I shut off that zone and put on the smaller one with seven radiators on it and within minutes the system "pumped over". That's the first time is pumped over in two to three days. Could it be something to do with the zone valve?
I remember reading a post some time ago on another forum where I was told that the reason why the system was pumping over was because of the amount of sludge in it?
Thanks again guys

 

[dancinplumba]

is the pipe you call 'vent pipe' an 'overflow pipe' ?
thats what it looks like,if so there doesnt appear to be a vent pipe

 

[dancinplumba]

where do the 15mm pipes go above and below the pump ??

 

[SafeGasInstall]

I personally think , luck of maintenance has ruined your system . Its time for full upgrade ! From boiler to pipe work if it's badly sludged , old rads can be washed down ! New controls and convert to sealed system !

 

[teejay246]

Sambotc, seems to be ok with the head as iv asked that, but Teejay, how much distance do you have between the open vent highes point, and the water level in the f and e tank?
And yes, as above Teejay, some clear pics mate would help Masivley...

Sorry Bren, the penny just dropped. I was picturing the "open-feed" to be the "overflow". You probably mean the pipe where the fresh "top up" water goes down to the rads from the F+E tank?? In which case I need to check the level that the ballcock is at? I hadn't thought of that. Thanks. IU have a suspicion it's too low. Also forgive the funny words in last reply ( speech software is great most of the time )
There is crud in the F+E. I emptied some out last year but need to look at that again.
Whenever I bleed anything on the system, I lock open the M.valves.
I will check the water level in the F+E later. Is it better to do this with sys ON or OFF, warm or cold?
Thanks

 

[Brendan Rodgers]

No mate, I mean ther should be a pipe over the TOP of the tank, and the highest point of that should be 450mm minimum from the water level, in my last comments I said ,It can't breath,, and you also like I said before should have a bypass between flow and return before your zone valves, short piece of pipe normaly with a gate Galve on it.. All ,S,plan systems should have one. It seems that's what you,v got.
also from what your telling me you,v either got a blockage in one of your zones and when it pumps over, that's when you get your air in.
my advise to you is get somebody local you can trust, a power flush and upgrade, it will cost a bit but worth it.

 

[Brendan Rodgers]

JUST SPOTTED IT,,,, got no open vent,,, update to sealed system, expansion vessel, safety valve and pressure gauge, also get it power flushed first or you,ll be at it for weeks, ther,s all sorts wrong with that mate....,No bypass, no open vent, blockages somewhere, ect....
Bren....

 

[Nostrum]

Your 'Rad feed' pipe looks like 28mm in the loft, but both the connections in behind the pump (one on top of the tee, one which runs parallel under the pump then tee's in) are both in 15mm?

Does this 'rad feed' pipe reduce down, or does it connect in somewhere else?

Pic's would help (maybe a bit bigger than the last ones!)

 

[teejay246]

Reply to "dontknowitall" who said: "To give some examples, I bled the air from a heating system a couple of days ago. The bleed valve was about 10 feet up in the airing cupboard, hidden in the corner. Another house I've been to has two bleed valves in the loft as well as another on the first floor. Other houses don't have a bleed valve and rely on the heated towel rail to collect the air in the system."
I have the towel rail arrangement. On rare occasions it goes stone cold with air. There is no vent on it but the rail is connected to the pipe with the auto vent on it in the loft. When that was gunged up I had probs with towel rail as well. With the new float type vent working, towel rail works great.
Sambotc: The rad feed is actually 15mm connected to one of the CH pipes from the "boiler room". The fresh water feed above it is also 15mm.
Talking about the F+E and following a comment made earlier stating that there could get into the system only through the "open the event" -- believing, obviously wrongly, thanks Bren, that the open vent meant the feed entry, I decided to check the level of the water above this and found that it barely covered the aperture, at cold. So I adjusted this giving 25 mm approx, having thoroughly cleaned the inside of the tank and removed the small amount of sludge. Put a new washer on the ballcock valve, then with the M.valves locked open I checked all the radiators for air. That done I switched on the system and it has been running silently ever since -- but that is only a few hours so I will need to wait and see how long this silence lasts. BUT, first thing this morning when the system fired up after being off all night, I got about a litre out of the overflow into the drive as the water heated. Apart from that all the rads are nice and hot except for one -- it is one nearer to the boiler and it's normally one of the first radiators to heat up. It is warm but not as hot as the others -- even the ones furthest away. I tried bleeding it but there is no air in it. On past performance, I don't expect the system to pump over ( overflow) again unless I turn on the bigger zone. That said, when I restarted the system last evening and ran it for the last 4 hours or so before bed, there was no "overflow". With this system running, I note that the water level in the F+E is only about 5mm from the overflow pipe. So very little tolerance here ( the F+E is as high as it will go against the rafters too ) and maybe having raised the cold water level so that it is 25 mm above the rad feed, that has also affected overflow? But so far, nice and quiet and no air apparent. Later today I will try to draw a schematic of some kind of how the system is laid out. Not easy because it's all covered in insulation and there are two or three pipe chases -- two pipes deep in places.
I am only too aware that I really need someone who understands old systems and who can be trusted to take the time to cast his experienced eye over the whole thing. I am making enquiries. I have some experience of friends who have had new systems installed locally and up in Glasgow. All of them have had and continue to have problems and all were combi systems. Mine is a big ole house with two bathrooms and a shower room. At present, apart from the lack of a trustworthy, proven pro, we also have a lack of funds. One can imagine our reluctance to use our savings on an "upgrade" when we may never be done with probs from it. Thanks for all the help so far guys. Its appreciated and I am learning. By the way I am in Prestwick, Scotland.

 

[Brendan Rodgers]

Wow...

 

[Nostrum]

....except for one.....

 

[dancinplumba]

eh ??

 

[teejay246]

teejay246 🙂

sounds like you've done yourself some research or know a bit or too?

You mention 2 zones. How is your hot water heated?

After checking the level in the F+E cold and adjusing it. It's sounded less "airy" BUT still getting some air being dealt with constantly by the float chamber. Still pumping over at start up though.
Put in X400 and am letting that do its job for a week or two. Rads are hotter and more surface on the old ones heats up.
Decided to take time to map this old system. Took some time and here is the pic. Surpised to find the cold feed tees into the hot water for starters.
I suspect a faulty zone valve too. When off, the pipe below is warm and there is warmth in one of the rads at the top of the circuit. Not a lot but should it be??
Also my Grundfos pump ( 1yr old ) needs the bleed screw tightening a heck of a lot to stop weep from bottom of the black name plate. Grundfos say the casting may have a hairline crack in it. It's not leaking at present - what do you think?
From the diagram would you conclude that the HW tank has a coil in it? Could that be the issue even without any apparent colouring of the hot water?
Getting a pro in now I have a diagram ( hope I tracked everything major properly ) Also discovered the open vent out on the roof ( plenty of height ther I think. Well its all worked well for many years.
Hope you can see this picture OK will it be far too small? It was an A4 doc?

 

[teejay246]

Hi guys
Been monitoring the whole thing for a few months. Seem to have isolated the "air problem" to the HW circuit. On it's own the HW circuit is not heating the water as it should. No more than tepid unless I run one zone of the CH. Noticed that the pipes below the zone valves are warm/hot even when HW is on alone. CH system runs perfectly, rads hot etc. and little if any air. Only get noisy at the pump when running HW only??
BTW: Bought new zone valves- after 30 yrs the old ones don't owe me anything but will need the pro to install them. Controller is sending the message to the ZVs. Pro reckons the old copper tank was so heavily built it will outlast my house, coil in it - same and scrap- it's worth a small fortune.