Plumber connected up surrey/techflow flange wrong way?

[mike42]

Hi

Our shower was installed (not by me) two years ago. It uses hot water from a large hot water tank that is pumped out by a techflow shower pump. The pump is postive pressure, sits at the base of the tank and feeds 22mm pipework all the way to the mixer.

The problem is that it takes 5-10 minutes to reach full pressure/flow!

Due to leaks and other reasons I have since replaced the concealed mixer (re-tiling etc) and flushed the pipework of all the black plastic trimmings present kindly left by the plumbers who also installed a new cold water tank. I also removed a 22mm-15mm-22mm constriction (god knows why they put it there...) and a hidden, underfloorboards compression fitting.

I now think the issue might be air and it only just dawned on me that it might be an issue with the way the techflow flange has been installed (its the one that fits at the top of the tank). The 22mm top outlet feeds the shower and it's side outlet is connected to the rest of the hot water in the house.

So my question is, does that matter or should it be the other way round? Could it be causing the 5-10min delay in getting a decent flow out of the shower? If it might be that, could it also be worth replacing the techflow for a proper surrey flange since I read the techflow has a short pipe and our cylinder is quite a lot taller/bigger than is usual.

As ever, thanks a lot in advance for any useful advice from the trade or experienced DIYers.

 

[mike42]

Can anyone help?

 

[mfarrow]

Have you considered the problem anything to do with the cold water instead? The valve is thermostatic of course and so will cut off either side where insufficient flow is provided.

A Surrey flange will help as currently you're likely drawing some if not all the water from the vent pipe on the tank outlet. Also the top of the tank is where any air bubbles will collect but I doubt that's your problem here.

 

[Hugh Jaleak]

I would as a matter of course, be expecting the top outlet on these types of flanges to be connected to the vent and DHW outlet! Air rises, hence why a cylinder is configured with vent constantly rising from the top of the domed cylinder to above the cold storage cistern, to allow any air to escape!

Taking the pumped supply from the top at very least will allow the pump to draw any collected air, causing cavitation and/or premature failure of the pump. The connection to the pump needs changing to make it correct as a matter of course, cannot say if it'll improve your current problem until you try it but it is certainly unlikely to make matters any worse!

If you reconfigure the pipework, you may need to alter the current vent/DHW feed to allow the correct rise from the cylinder, I suspect the shower installer connected the flange as he did to avoid making major alterations to the vent pipework.....

 

[mike42]

Firstly, many thanks for both of your helpful replies.

mfarrow, I'm not a plumber or engineer but I don't think the problem is the cold water because if I turn the thermostatic to cold only, I get good flow/pressure from the start. It is only when the water is hot does the flow come out at a reduced rate (that then increases 5 to 10 minutes later).

Hugh, thanks for your advice too and granted it might not be the cause of our troubles but I think after nearly 2 years of checking everything I think that is all that is left. I've taken a picture to show you the existing pipework. Apart from the pipework being connected to the top of the tank the wrong way round it looks like the connection to the vent follows a downwards path before going up again. I don't know what the venting requirements are but I would guess that it should not loop down like that?

Airing cupboard

• mike42
• 28 Oct 2014
• 1

 

[St0rmer66]

It definitely should not loop down like that! It won't vent any air like that and with the pipes the wrong way your shower pump will be sucking up every bit of air! (no way that little auto air vent will keep up).

What a terrible job he's done there . Plenty of room in the cupboard so it wouldn't have been too much work to do it correctly, I suspect incompetence rather than laziness!

 

[mike42]

Unfortunately, I think you are right - I've had threads going back since installation mostly about the poor quality bathroom installation. I've learned my lesson to always get people I know will do a good job and not always focus on price.

Anyway, this is where I am. I'm ok with pipe work (the doing not the planning!) especially where there is room as you say. Regarding the shower pump it seems there is nothing special to be done except connect from the right connection on the flange (!) ?

And regarding the vent pipe, do I just need to make sure no downward sections? I mean I don't think it can go straight upwards because the tank is directly below the cold water tank in the loft so maybe a horizantal 22mm pipe to the existing painted vent pipe on the left would be ok?

Finally, regarding the hot water feed which is 28mm, would it be ok to just use the a bit of the vent pipe as above? i.e. the Hot water would be 22mm exit from the tank sharing the route with the vent until it hits the painted pipe on the left? I guess its not ideal given the main HW pipe is 28mm below the wooden baton on the picture?

 

[St0rmer66]

Tee the top pipe from the flange into the vertical pipe with the vent (the painted pipe you described), keep it at least horizontal if not rising (even a tiny rise by just flexing the pipe upwards as you install it will do). Get rid of the auto air vent from the pipe. 22mm pipe will be ample, no need to do it in 28mm.

Then connect the lower/sideways pipe from the flange into the existing shower inlet pipe. Shouldn't need an auto air vent since it's from the flange. But make sure you prime the pump first and clear as much air as you can first by running the shower with the pump switched off after refilling.

As you can hopefully see, this would have been no more difficult than the current setup so the installer(s) have no excuse really!

 

[mike42]

Cheers St0rmer66 !! I think I understand what you recommend and intend to do it this weekend.

I've attached a new image of what I think you were saying just to double check I've understood correctly. Does it look about right? Also, should the red pipe be done in 28mm to match the existing pipe or you think its really not necessary (feeding 2 bathrooms, kitchen and cloakroom).

Untitled

• mike42
• 29 Oct 2014
• 1

 

[St0rmer66]

You only need the blue and green pipes. No need for the red. Do the blue in 28mm if you feel you must but I think 22mm would probably be fine given that you have a separate shower feed.

 

[mike42]

Hi

This is really just to say thanks again for the advice. I've uploaded a pic of the work I did today to rectivify the situation. Its too early to tell if it fixed my original problem since it was always a little intermittent.

new pipes

• mike42
• 1 Nov 2014
• 1

I decided to use 22m only and I agree there have been no ill affects because of it (touch wood so far...)

I did find myself wanting to refit the auto-vent on the shower inlet but didn't have any reducing tees of the right size to hand.

Also, I didn't have a 1" male to 22mm coupler for the top flange connection so re-used what the "plumber" had made up.

Main thing I'm slightly worried about is that I realised later that he had soldered that 22mm elbow on the top ot the tank so that if anything the resulting pipe was pointing down. That meant I had to really force the compression connections a bit to get the upwards angle. I used LSX on the olive and hoped for the best. I hope it doesn't blow out or something!


As you can see I used solder ring everwhere. I know its a bit "DIYish" but I'm still not confident enough with end feed and I think it does the job just as well (and certainly a lot better than regular compression or pushfit connectors if you know you won't need to undo them)

untidy connection

• mike42
• 1 Nov 2014
• 1

 

[St0rmer66]

If it does the job and doesn't leak then I wouldn't worry how it looks . Yorkshire fittings are still better than Compression all over the place. It would probably leak immediately if it was going to leak but just keep an eye on it, you'll know soon enough. Very unlikely to just "blow".