4 plumbers out and no fix. UFH not working downstairs. Return pipe cold

[Temp]

On 20/12/2023 at 09:18, ProDave said:

So when he turned the temperature down you got flow.  It sounds to me like a problem with the temperature blending valve then.  When it reaches the correct temperature it should stop drawing hot water from the boiler and instead just circulate the water in the loops until it cools down a bit, when it will then let a bit more hot in from the boiler.

 

I would be changing the blending valve as my next step.  Surprised none of them has suggested that.

 

+1

 

If the supply to the manifold is hot, the actuator(s) are open and the pump is running then something is blocking the flow.

 

Two possibilities are..

 

1) Sludge in the pipes. How good a job did the plumber do in flushing the system?

2) The mixer/blender (on the left) is faulty.

 

The only other thing I can think of is that the pump was faulty and they put the new one on the wrong way around. Check the arrow on the pump and compare with your other manifold.

 

 

[Gus Potter]

I'll chip in as the Philistine. I've said for years that all these complex controls on UF are a waste of time. They work fine for a few years, break down and then no one can fix then at a sensible cost. After while even the folk that have installed them.. yes even you BH folk then forget how they work and the nuances of your wiring up of the controls.

 

I've designed a few UF systems in the past, always go for the simple stupid. Here is a knock up manifold made on my most recent house (photo is from 2020).. still working and have just extended it. It is a lot bigger now I have added more circuits and some basic controls. Now I know some may say you can't use gate valves.. I say they cost a couple of quid to replace if they start to weep. I know from experience that, as I did the same 20  years ago and times since, that this Flintstone stuff works, and folk can understand it. Lately I've added some extra electronic controls but these are not related to the pipework!

 

Happy to take the pelters for my views.. !

 

You may think I'm bonkers but it was just something I know would work and made from fitting I had in my plumbing stock box. The biggy though is the blending valve. I have fitted an few of that type for other folk in the past and I know they are reliable. Also It's a 28mm blending valve so oversized to some repsects as it going onto 22mm pipework.. but my thinking is that any gunge will pass though it so I paid more for a bigger 28mm valve.

 

My big mistake was to have some HIVE controls.. little did I know that I would have to keep updating the software and that if I move house I can't take them with me or some other shite like that. I learnt a lesson.. these are fundamental part of the house / structure.. DON'T trust them to third parties.. you could devalue your house a lot.

 

 

 

On 19/12/2023 at 23:32, Markca said:

This one is driving me mad.

Hi Marka.

 

Before you start mucking about make sure your filters (nowadays mag filters) are clean and working ok. You probably have some kind of gunk / blockage coupled with those controls that we are all told will work for more than 5 years, the life of the system, like I stilll believe in Santa.. You don't want to shift the problem and say block your fancy heat exchanger on your boiler. Just before start to muck about incease the pressure in the boiler circiuit, say to 2.5 bar and operate the safety relief valve to clear that out and give you piece of mind.

 

I would be tempted to isolate the manifold and connect a garden hose to the return (cold) drain cock at the RHS of the manifold, disconnect one loop at a time and back wash it.. You must back wash as if you get this wrong you'll really have a problem on you hands.  You'll flush a load of crap out of some of the loops and it will make you feel good. Your average Plumber just can't spend the time to do this... you can!

 

Now a few ball park sums:

 

I think the pump you have can at top end with negligeable flow raise a column of water to about a 6.0m head. 1 bar of water pressure is about a 10.0 m head, thus your pump can deliver about 0.6 bar. As a bad case your hose pipe can deliver about 1.0 bar say.. this is should be enough to push back some of the gunk that you have loitering in the pipes.  Try this first as it's a great feeling to see crap coming out the pipes.

 

Connect it up again and see if it works. Now the thing with the hose pipe.. it gives you confidence as you know the pipes runs are clear. I tend when back washing to run the flow into a bucket so I can see how quickly each loop fills the bucket. If you know the loops are clear and now clean.. you have not just narrowed the problem down but given the system a good clean in the process. You can also time each loop to fill the bucket so you can then compare that to the flow meter in qualatiative terms.

 

While you don't know pressure from the garden hose it allows you to compare flow rates against the hose pressure. If you want to get tecky the bucket flows should correlate to the differences in the flow meter readings. The main thing is to keep a note so you can then tie that back to any problematic sticky valves.

 

I have mucked about with loads of these systems you have, flow meters / valves etc, for a few days they work and then break down again.. it will drive you nuts. You need to get it clean, then you can identify the sticky bits / valves which will give you the best chance of a long term fix.

 

I'm sure you can do this .. but you need to be patient, set aside the time to do it and enjoy the investigation process. At the end you'll fix it and have a much better understanding of how it all works.

 

If you are going to take things apart the use a non setting jointing compond to put them back together again.

 

https://www.screwfix.com/p/flomasta-gas-water-jointing-compound-250g/7619J?tc=IT5&ds_rl=1241687&ds_rl=1245250&ds_rl=1249404&gad_source=1&ds_rl=1245250&ds_rl=1247848&ds_rl=1248151&gclid=CjwKCAiAp5qsBhAPEiwAP0qeJgeoDPCPpzi5pclPe4Z7WOvVn2L3w6jg_YEaMtCIxGTkJzNUkg39uxoCZGMQAvD_BwE&gclsrc=aw.ds

 

To conclude.. your system probably has a bit of crap in it, each time you try and tinker you'll probably shift the problem somewhere else. The flow meters and complex controls are probably not playing the game.

 

Clean it out yourself, have fun, and save loads of cash!

 

 

 

 

 

 

 

 

 

 

 

 

[SteamyTea]

It is a shame that there are not decent drawings of plumbing systems and all the pumps/valves/controlled gear that was originally installed.

 

I am with @Gus Potter  KISS

[joe90]

2 hours ago, SteamyTea said:

I am with @Gus Potter  KISS

+1, even our Jeremy Harris dumped his complicated control system for a simple room stat.

 

[SteamyTea]

I use this as my automation.

 

It is useful as it can switch devices, sense moisture and temperature, and tell useless plumbers to (expletive deleted) off.

And I have spares.

[HughF]

Pump runs 24/7 at 30 degree flow in my place, I’ve just wired it to a switched-fused spur…. Heat pump runs 24/7 on weather comp too… not a single wall thermostat in the whole place.

 

trvs in the bedrooms, that’s it.

Edited December 24, 2023 by HughF

[Markca]

Okay guys I’m back and the problem has got worse. 
 

The boiler is now showing error codes of H5 (maybe HS?) and F6. Both suggest it’s water flow and blockage. 
 

Now all systems (upstairs and downstairs UFH that are on different manifolds / pumps) have stopped working as well as the hot water. The boiler will show a temp of about 17c. 
 

part of me thinks this is bigger than my capabilities so I might have to get another plumber out. 
 

if I do remove the blending valve to clean it, how do I do this? 

[Markca]

Spoke to one of the previous plumbers on the phone and worked out we can get it back to how it was before when the hot water is turned on all the time. So it’s back to square one 

[ProDave]

44 minutes ago, Markca said:

Spoke to one of the previous plumbers on the phone and worked out we can get it back to how it was before when the hot water is turned on all the time. So it’s back to square one 

So are you saying you HAVE done that and and it is now "working" again?  if so tell us what he did please.

[Markca]

32 minutes ago, ProDave said:

So are you saying you HAVE done that and and it is now "working" again?  if so tell us what he did please.

We reset the boiler and turned the hot water on via hive

[TonyT]

Your fault codes can be looked up online, don’t think you get an H code, the other looks like it points to an external temp sensor.

 

has any of the wiring been altered recently since the installation was completed?

[Markca]

So it looks like the blending valve was indeed blocked!! I’ve just done this myself, removed the bits (which are little bits of stone I think?!) and the water flow gauges are now all working. It’ll take a while to warm up but I really hope that it’s fixed it. 
 

thank you so much everyone - I’ll report back later 

[Russdl]

Good luck.

Really really shoddy installation or is something breaking up in there?

[Markca]

1 minute ago, Russdl said:

Good luck.

Really really shoddy installation or is something breaking up in there?

Pretty sure it’s from installation. When it was first fitted it used to rattle in the pipes and I was told it was normal, but I’m not sure it was 

[Russdl]

Do you have any recourse to the original installer?
 

If your simple cleaning job fixes it, perhaps they can pay for all the additional (ineffectual) call outs you’ve had. 
 

I wonder if all the crap in the system has made it’s way into the blending valve or wether it still needs flushing. 

[MikeGrahamT21]

Wow no wonder it wasn’t working, I’d expect that to fill up again some more going on the amount there.

 

likely will need a proper flush asap

[ProDave]

That's lucky you hopefully have fixed it.  I speak from experience that it can sometimes be difficult finding an identical blending valve.

[Markca]

The house has warmed up and stayed warm! I’ve booked the original plumber to come and do a full service in the new year and flush the system (mostly so I can see him squirm). 
 

im going to clean it again in a couple of days and see if it’s got anymore in. 
 

thanks again everyone 

[Andehh]

Well done there, will be very satisfying once this saga is over!!

[Mr Punter]

Well done @ProDave for diagnosing the issue within a day of the original post.

[ProDave]

2 minutes ago, Mr Punter said:

Well done @ProDave for diagnosing the issue within a day of the original post.

I wonder why the plumbers did not diagnose that?  Could it be they were not 100% sure and did not want to look silly / carry the cost if they replaced it and it did not fix the fault?

 

As it happens it was blocked with debris so there was no cost in removing that to fix it.