My heating's been pumping over for a while now, spilling over the overflow from my header tank. I can't seem to get to the bottom of the problem.
I've extended the height of the open vent which is now two feed above the t op of the header tank. I have also bent the arm of the float valve so that the water level in the header tank is about five inches high, but it still pumps over and out of the overflow.
I recently put fernox F3 through the system, flushed it all out and re-trea ted. I also descaled the boiler using fernox DS40 as part of the same job.
I have read that the aerjec air separator things can get blocked and cause pumping over, but I'm not sure how I would re-pipe it if I removed it, or p erhaps it isn't a problem?!
Here's a photo I took of my pipe setup in the airing cupboard (ignore the l eaky hot tank, that was quickly replaced):
I am told by a plumper aquaintance that you shouldn't get pumping over if you have an aerjec. In fact I recently fitted an aerjec after a long period of pumping over and it cured it. When I cut out the existing pipework to fit the aerjec I found the flow mostly blocked with a crystalline structure immediately after the old feed. It was rock solid
- can't imagine F3 or anything shifting it (and I did put some cleaner in at one point). (Of course, the aerjec might have had nothing to do with curing my problems - replacing the partially blocked pipe might have done. Unsure as to cause and effect here.)
Note that the aerjec instructions state that the vent must be vertically upwards. Pretty sure yours is horizontal. See
It looks like the vent is on the suction side pump... is that right? (make pumpover unlikely - although can suck air into the system)
Sometimes making a combined vent and F+E connection on the suction side solves the problem. So you take the F&E pipe and tee it into the vent a foot or so above the CH vent connection.
Yes I think you're correct. As Piers has indicated, the installation of the Aerjec is likely incorrectly oriented, rendering it useless.
Make a "H" type of piping setup linking the F&E to the vent? What would you reccommend doing with the Aerjec? (bearing in mind I'm reasonably sure it's blocked).
Have you actually watched water discharging from the vent pipe into the F&E tank - or are you surmising that it does because it's going out of the overflow?
What is the difference in level between the level controlled by the ball valve and the level needed to overflow? If this difference is large (say > 6") the static level is unlikely to increase by this amount just due to expansion. Even if pumping over *is* occurring, that in itself won't raise the level in the F&E tank - so if its rising above the overflow, something else must be happening.
Is there a large cold tank in the attic, as the header for the DHW system? If so, how does the water level in that compare with the level in the F&E tank. If it's higher, have you considered the possibility that the coil in your hot cylinder may be shot - resulting in water from the DHW system leaking into to primary circuit?
I'm not sure the arrangement show is a good idea. A favorite place for lime scale to form is where the feed joins the main loop, some one in here has already mentioned that from their direct experience. In the above layout if that stub between the main loop and vent/F&E gets blocked things could get "interesting" as it would also block the vent...
This is a more common arrangement, the space between the vent and F&E should be < 100 mm:
As you can see from the photo of my airing cupboard, there isn't a whole lo t of room to play with in terms of current pipe layout. The hot feed from t he boiler comes up from the floor in parallel with and within an inch or so of the pump itself. I'd have to tee in either the vent or the feed from th e F&E tank in there to go with the layout you suggest.
Would you recommend I tee in the vent at the top, where the Aerjec is now, and the cold feed below it, tee'd into the rising hot feed?
First off, get yourself a magnet and check all the pipes around the cold feed.
If there has been a longstanding leak, the limescale will precipitate at the point where the cold water enters the heating system, forming a solid blockage with magnetite sludge.
The standard remedy is to cut out the Tee and replace it.
You might be able to descale the Aerejec thing, but I'm told descaler is ineffective on the magnetite/scale deposits and I've never tried it.
the point where the cold water enters the heating system, forming a solid blockage with magnetite sludge.
ineffective on the magnetite/scale deposits and I've never tried it.
There isn't a problem with the hot water tank. The height of the water in t he header tank drops to a normal level when the system is cold. I've checke d with a magnet and it's all ok. I also fitted one of these a while back: h ttp://
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I could replace the Aerjec for £12 but most things I've read suggests the y are better off removed. Plus, it looks like mine's been fitted incorrectl y by the plumber when the house was built, and the plumbing doesn't lend it self to being majorly re-configured.
replying to Tom Pickles, Brian wrote: Hi tom i have taken a look at your aerject layout in the picture posted and straight away i can see where your problem lies , if you look at the pump you will see that the grundfos logo printed on the front of the pump face is upside down and the speed rotation arrow printed near the bleed screw in the middle of the pump is showing the pump turning anticlockwise , therefore this pump is actually fitted upside down meaning the positive pressure of the pump is forcing water from the return side of the boiler into the aerject causing the water in the vent pipe off the aerject to rise above the expansion tank level and over into the tank as steam/water when the boiler is working at maximum temperature.The purpose of the aerject is to reduce excess negative and positive pressures being created by the pump by virtue that the open vent pipe is taken close to the neutral point of the system which is always where the cold feed from the expansion tank connects into the system , in addition to this the aerject has a 22mm port ontop to remove air bubbles as the pump sucks water through the device and this is achieved by slowing the water flow down as it enters a larger void spave within the aerject reducing the velocity pressure and giving time for the air bubble to rise out of the aerject void space and out up the vent pipe and into the atmosphere above the expansion tank. So my suggestion would be to turn the pump the right way up and if problems still persist to re pipe the aeject making sure the vent port is facing upwards and your flow from the boiler goes into the top side connnection the flow to the heating system goes directly below it on the same side and finally your cold feed pipe goes to the connection opposite the flow connections to finally resolve your problems, dont forget to desludge your aerject completely before refitting , hhope this was useful to you and your fellow engineers,regards Brian (Domestic boiler technician)
Clearly you've given a detailed and well-meaning response to Tom's problem, unfortunately it's over two years too late ...
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replying to Onetap, Kevin. Professional domestic gas tech and heating consultant. wrote: Hi guys, I would like to add: if the water colour in your system is black, that?s hydrogen deposited as sludge in your system once the water has become over saturated and released as much as it can as hydrogen gas. You may have bled the radiators thinking it was air. A good de-sludging non de scaling agent, X100 or furnox will do. If the water colour is orange or red, that?s due to air entering the system via the header tank for the heating system. The desludging agents mentioned will have little affect on this. You need to have the system power flushed and this can take up to a day or so. The ?pumping over? is mainly due to a low pitched roof which prevents the header tank to be installed at the correct heigh. The Fill and Vent should not be installed by the use of tee fittings. A Myson airseperator or a Tower Air separator should be installed correctly and the distance between the exit of this peice of equipment and the first pump valve is crucial. If the ?pumping over is the main problem, before you spend money, check for a blocked cold feed from the tank to where it enters your system. It really is a professional job yet be ware of rip off merchants. Also when this work is done take care of your system and do not trust the nationals out there who are only out for your money. Kindest regards.
replying to Onetap, Kevin. Professional domestic gas tech and heating consultant. wrote: Hi guys, I would like to add: if the water colour in your system is black, that?s hydrogen deposited as sludge in your system once the water has become over saturated and released as much as it can as hydrogen gas. You may have bled the radiators thinking it was air. A good de-sludging non de scaling agent, X100 or furnox will do. If the water colour is orange or red, that?s due to air entering the system via the header tank for the heating system. The desludging agents mentioned will have little affect on this. You need to have the system power flushed and this can take up to a day or so. The ?pumping over? is mainly due to a low pitched roof which prevents the header tank to be installed at the correct heigh. The Fill and Vent should not be installed by the use of tee fittings. A Myson airseperator or a Tower Air separator should be installed correctly and the distance between the exit of this peice of equipment and the first pump valve is crucial. If the ?pumping over is the main problem, before you spend money, check for a blocked cold feed from the tank to where it enters your system. It really is a professional job yet be ware of rip off merchants. Also when this work is done take care of your system and do not trust the nationals out there who are only out for your money. Kindest regards.
Yup might have been a handy response if were not for the fact you are FOUR YEARS too late... Do you suppose looking at the date of the original query would not be a good idea?
(especially as most people reading this won't even know what you are replying to!)
One *single* entry in my killfile blocks every single HOH posting. The only evidence of HOH postings I ever see are in quotage in follow ups like this one. Since there's virtually zero benefit in replying to
*anyone* posting via the HOH portal, killfiling HOH postings seems the kindest thing to do for all concerned. Just a suggestion. :-)
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