Feed and expansion tank/cistern and few general system questions.

[Fandyman]

Hi,

I've got a leak coming from the loft into a bedroom which I think is caused by water overflow from feed and expansion cistern (see attached one of the photos when I found out the cistern overflowing above the overflow pipe) and one other pipe that has a small drops coming out of it that is not a major concern for now (but maybe pressure problems in the sytem?).

What confused me is that overflow pipe is not working properly as I should never observe the F&E cistern to overflow like it did. I cannot localise where the water should be discharging above certain level as the piping is confusing (I think the overflow pipe is the white one on the attached photo). Something for sure must be blocking the discharge which is unclear to me or could it be the F&E cistern does not have a discharge outside of the building and into a drain?

The other thing is there is no isolation valve on the ball cock valve so if worse comes to worst I have to switch off the mains to the house from the street level as the overflow pipe does not seem to be getting rid of the excess water and the cistern may overflow again.

I've stopped the main leak for now by emptying the water from the F&E cistern to leave it at 1/3 full so no overflow is happening. The pipe that shows signs of small drops still leaks slowly but not causing major problems.

I've purchased the house 3 months ago and even though I asked for some explanation on the heating system the previous owner was not able (or did not want) to reply.

The boiler that I have is Baxi 80HE Plus but it is some sort of standard (system?) boiler. One of the other things that I would like to know is what type of heating system I have? Is it possible to tell from the boiler type/model itself? I know I have a cold water tank and hot water cistern with F&E water cistern in the loft. There is a lot of piping and it is hard to make anything out of it without so guidance. From some googling online I suspect I have open vented central heating system with regular boiler.

Also, the boiler does not have any pressure gauge which is understandable with some regular (non combi) older boilers but I cannot find a pressure gauge anywhere else in the system which seems strange to me. Should there not be a pressure gauge anywhere near the boiler or anywhere else accessible?

Other than that I cannot localise any mains stopcock in the house. I tried garage cupboard with all the meters, area in garage around boiler, under kitchen sink and around downstairs toilet and I could not find it anywhere. Is there any other location or is it possible there was no stopcock fitted inside the house. The previous owner did not know where it could be when asked. I still find it bewildering. The only things that the owner told me were that there was underfloor heating installed throughout downstairs (no idea if electric or wet version - never answered), replaced hot water cylinder with a new one and installed automatic pumps for the showers and bathtub.

As for the underfloor heating - is there any way to find out, other than looking under the floor boards, if it is electric or gas powered?

 

[gmartine]

Ask a neighbour in a similar house/flat where the stopcock might be, yes you have an open vented system with a regular boiler which is unpressurised so you won't find a pressure gauge.

The overflow is the white pipe which in a normal configuration will usually be exiting the the loft via the eaves so have a look under the guttering where it looks to be exiting the roof. The tank connector needs to better sealed or tightened as you can see from the deposits that it's been leaking.

If it's a wet UFH system there should be an accessible manifold somewhere, electrically powered not so much but check the consumer board as it may have it's own isolator.

 

[Fandyman]

Thank you gmartine for your response. Appreciated.

I've had an engineer come and install a new ball valve with isolation valve.

One thing that surprised me is he initially only wanted to install the ball valve. When I asked whether he would install the isolation valve too so I could do some maintenance on the tank he was not sure why I needed that (I did my homework and explained why). He finally agreed to do that. I am baffled as to why he would not think this tank needed maintenance (at the end of the day we want to have as few problems with it as possible - unless it is a lost job to him?). I've seen plenty of videos on youtube showing how to clean F&E tank and the reasons to do it.

Another thing that he fixed was a leaky overflow pipe. Strangely he did not want to test it afterwards and when I asked why he said there was no way he did it incorrectly which again makes me wonder why would he not test his own work. I am still to test it myself to make sure if this happens again there is no nasty surprises in the bedroom downstairs.

The conversation about F&E tank maintenance brought me to some questions which he did not answer:

1) Should the tank have a lid and be insulated? The tank I've got there has no lid and a lot of muddy water on the bottom and sides which can surely pollute the heating system and cause corrosion and blockages (from falling insects and other debris etc). When asked he did not reply (which I found strange) but said power flushing is expensive £600-£700 and he does not think I need it.

2) From some photos I found online it seems that the hot water cylinder has CH piping that go through. Is a scenario possible where the water from CH and DHW mix causing dangerous condition at the water taps (would that be why kitchen tap is the only drinking water that should be ever considered). How likely is it to happen? What are the signs of that? Is the benefit of additional heating from CH worth the risk of polluting the DHW? This makes me think keeping the open vented system like mine clean which is the more important then before (e.g. occasional maintenance of the F&E tank).

3) The hot water cistern has a thermostat on it. Before the engineer came it was set up at 40C. He turned it up to 55C. What is the ideal temperature and why? Apart from affecting the temperature at the taps, bath and showers does it in any way make the hot water at the taps appear faster? I suspect not and it is the pumps that are needed but just wondered. Apart from having low pressure from the taps my main problem is that I have to wait around 45s to get the water hot in the upstairs bathroom which is supper annoying and wasteful as well. Would adding another pump to that flow fix it?

4) I read online that system like Megaflo is very popular and I think it would give me the water pressure and space saving that I really would like in the house. How expensive would it be? Is it possible to install the cylinder in the garage and reuse most of the current piping. The other reason for it would also be to clear the space in the loft for another bedroom in the future.

 

[gmartine]

All loft tanks should have lids and be insulated.
55 deg C for HW cylinder is fine and is a required to prevent legionella.
The CH & HW circuits will not be integrated anywhere.
A megaflow unvented cylinder will allow you to position it almost anywhere and free up loft space but requisite mains water pressure and flow rate is required.
Get some quotes as a site visit is required.

Please try and keep further questions brief, tnks.

 

[Fandyman]

All loft tanks should have lids and be insulated.
55 deg C for HW cylinder is fine and is a required to prevent legionella.
The CH & HW circuits will not be integrated anywhere.
A megaflow unvented cylinder will allow you to position it almost anywhere and free up loft space but requisite mains water pressure and flow rate is required.
Get some quotes as a site visit is required.

Please try and keep further questions brief, tnks.

Thanks for your reply.

Regarding:

The CH & HW circuits will not be integrated anywhere.

I know the CH & HW are not integrated anywhere. What I meant there was whether it was possible the CH coil inside the hot water cistern (see attached) could perforate causing DHW and CH water mixing together? If system is not maintained and cleaned occasionally (e.g. missing lid from the F&E tank causing all sorts of debris falling in to it and travelling along the system with blockages and rust forming too) I can imagine the coil may be gradually corroding through oxidation and/or damaged/blocked by debris causing it to eventually perforate. If it is possible how do I know that could be the case?

 

[gmartine]

Is there a problem with your system?

 

[Fandyman]

Is there a problem with your system?

Yes - water rising and overflowing through overflow pipe in F&E tank regularly which is not caused by the ball valve which has been fixed now.

 

[plumbingservices]

Yes - water rising and overflowing through overflow pipe in F&E tank regularly which is not caused by the ball valve which has been fixed now.

Good to hear that your plumbing issue has been resolved!

 

[Fandyman]

It has not been resolved. What makes you think it was resolved?

 

[Fandyman]

The problem still persist - water keeps rising and eventually overflows.

As i understand on a correctly working system this should not happen and the water level should(mostly) stay at 1/3 of the tank capacity.

There's no leak from the tank itself now (I suspect it was caused by the frozen overflow pipe but was not able to prove it) but there is still a problem of water rising to overflow level and discharge through overflow pipe even though the ball valve is replaced now.

Other issue I noticed is there is almost no hot water pressure and flow in the upstairs bathroom taps. The showers and baths are ok but they have water pumps installed hence they have been always fine. The taps, however, is a mystery to me.

I have contacted the plumber who replaced the ball valve and he said it would not have been caused by him. However, I have got almost no hot water pressure and flow in the upstairs bathroom taps since his visit.

Any ideas?

 

[Ric2013]

The problem still persist - water keeps rising and eventually overflows.

As i understand on a correctly working system this should not happen and the water level should(mostly) stay at 1/3 of the tank capacity.

There's no leak from the tank itself now (I suspect it was caused by the frozen overflow pipe but was not able to prove it) but there is still a problem of water rising to overflow level and discharge through overflow pipe even though the ball valve is replaced now.

To answer your previous question, the coil could perforate and lead to mixing of water. It happens rarely and is very unlikely to be anything to do with the system water quality, though maintenance will obviously help make it less likely still. If the header tank for the cylinder is higher than the header tank for the boiler, then you may indeed experience the water level rising as described in this thread.

Other issue I noticed is there is almost no hot water pressure and flow in the upstairs bathroom taps. The showers and baths are ok but they have water pumps installed hence they have been always fine. The taps, however, is a mystery to me.

I have contacted the plumber who replaced the ball valve and he said it would not have been caused by him. However, I have got almost no hot water pressure and flow in the upstairs bathroom taps since his visit.

Any ideas?

I'm assuming you have two header tanks. If the cylinder feed cistern has been drained, then it is possible air could have got into the pipework to the taps. In theory they should be self-venting, but if there is poor pipework design, there should either be a manual vent somewhere, or you can try the old plumbers' trick of trying to backfeed the water through the affected taps using a garden hose to try to force the air to travel up the vent above the cylinder feed cistern. Or just run them a bit and the airlock will eventually clear itself as it sounds like there is a slight flow.

With regard to your earlier question about having to wait 45 seconds for water to your taps, a pump would reduce the time, but you'd still waste the same amount of water. Other solutions are a secondary return pump (look it up on a search engine image search for a diagrammatic explanation) or, as you suggest, a pressurised cylinder. Most of these solutions are quite expensive and if you actually want to reduce waste by increasing the pressure, you need to also have the pipe run made from narrower pipe.

If you're really lucky, you may find the system you had worked perfectly well in the past until someone decided to 'modernise' the house with taps that invariably don't give a very good flow with the few feet of pressure you most likely have. Old-fashioned taps that use washers and meeting the former BS2456 or BS1010 standards are still available (just about) and I have a bath tap of this kind giving me 22 litres/minute off around an 8 ft (standing) head of pressure. If you're unlucky, then the pipework will be creating resistance to flow, so changing the taps won't help very much. I suspect waiting 45 seconds for hot water, while far from ideal, is something most people will accept, so the installer may not have bothered trying to get this time down any lower.

 

[gmartine]

I forgot to add, the cylinder is stainless and from 2015 so very unlikely to be perforated or affected by corrosion. It'll take time for the HW to run through from a cylinder located in the loft, I'd say that was not an unusually long time to wait. The vent pipe looks a bit low so it could be pumping over more easily than it should, 18" above F/E water level and of course there could be a blockage somewhere.

 

[Fandyman]

Thank you for your replies.

Can someone explain why more powerful Combi boiler world not be ok to feed 2 bathrooms. I've read online there are such boilers and ppl successfully installing them in similar set ups to mine which makes me think I should not cross it out.

I would much rather have hot water/heating on demand than wasting energy through constant heating of water stored in cylinder.

 

[Ric2013]

To be fair, it depends on how the bathrooms are used. If multiple taps are run simultaneously then the risk is insufficient flow (or insufficient heat in the water) to feed all taps at the same time. More of an issue when showers are used simultaneously.

If, on the other hand, they aren't used at the same time or the required flow does not exceed the HW output of the boiler, it's not a problem, really. Make sure showers are the thermostatic type so the person showering does not experience wild fluctuations in pressure. Be aware this approach is 'wrong', but if it works for you, it may be a viable option.