Impossible to fix flow problem? 4 grand down so far...

[Old UKPF 99429]

Some of that pipework in the boiler cupboard a crap DIY job previous owner must have done to pipe in a shower pump. Not linked to heating circuit.

 

[AMGasServices]

I have uploaded a image how your systems should look but it is not 100% correct as there are a few things missing.

 

[Old UKPF 99429]

Thanks. So even so some of the pipe work is a bit shoddy right. There seems to be nothing fundamentally wrong. Flow up to pump, into auto valve and feeding dhw tank and/or rads. H/w and rads returns all into boiler cupboard. Pressure tank on return in boiler cupboard with filling loop...

 

[Old UKPF 99429]

Expansion vessel, not pressure tank! Couldn't remember the words.

 

[sammathias]

22mm equal tee before the pump what is that for ?

Looks like the old feed and vent, can only assume it's capped off higher up and not just isolated on that 15mm gate valve.

The flow and return does loop together by some form of close coupled tee arrangement.

If your certain that that motorized valve is working correctly and the wiring is correct it probably is a blockage 'solder' .

In picture 5 you could unjoin the two 22mm tees far right and see how it performs.

Basically with that complete mess it's going to be impossible for us and best to get a 'plumber' to rectify that pipework.

 

[Rob Foster]

It might be an idea to fit a second hand pump on the rtn, wire it straight to a plug, plug it in let it run all the time on fast and see what happens. 2nd hand pump is dead cheap

 

[Old UKPF 99429]

I have two spare second hand pumps! I wondered if that would be ok to try that?

 

[sammathias]

I disagree.

 

[Darren Jackson]

Which way is the arrow pointing on the pump body? Hard to see on your picture. Also if the boiler was connected when flushed it could be full of crap now. Might be worth cleaning out the hex, plate & F/R valves.

 

[sammathias]

Darryl I will ask again but reword it. How many connections/tappings/valves are there on the underside of the boiler?

 

[Old UKPF 99429]

Thanks again for taking time to respond. Got Viessmann coming out today to check the boiler.

Will check the pump arrow direction, and will confirm if there are any pipes and connections at the bottom of the boiler from memory just one, plastic pipe?

 

[sammathias]

Ohh hopefully they don't condemn that boiler then. Let us know how you get on and weather they resolve the problem.

 

[fixitflav]

connections at the bottom of the boiler from memory just one, plastic pipe?

That's probably to be the condensate drain.

Consensus is it's likely to be low or no flow causing the problem. Re-reading your original post, I would guess the system has never worked, and the old boiler would have been fine if the flow issue had been sorted.
Assuming it is low flow, it could be due to a blockage or maybe the way the piping is installed. A sketch of the complete system would be useful, but not easy to prepare as much of the pipework will be out of sight. On a working system you can get some idea by following rising temperature round the system, but that's catch-22 in your situation.
Keep us posted about how you get on with Viessmann.

 

[Old UKPF 99429]

So, Viessmann came and went. He was adamant (obviously) that it was a flow problem! In his opinion, it is a blockage in the heat exchanger. This is because it does indeed behave exactly the same on just HW as CH. Possibly caused by powerflushing the system with the new boiler connected (as was mentioned), so has flushed some gunk down in to the heat exchanger.

His suggestion, get the boiler powerflushed, or just heat exchanger removed and cleaned fully. Put a magnaclean or some kind of filter on the return...

 

[Old UKPF 99429]

He only determined it by measuring flow and return temps. But was sure.

 

[Rob Foster]

so no result thats boring and AUTUMN is approaching. You will have to get someone in and maybe pay. See what the collective wisdom here says again. And then who ? cause you have done that ! hmmm

 

[Rob Foster]

I was again going to offer to look 'at cost' if you are not too far away cost wise and give you a contact no but your settings are precluding this -

 

[Old UKPF 99429]

Not shy of paying if that is what the implication is? Already had two plumbers/heating engineers out, approx 8 visits, maybe 4 days of work. Cost of 3.5k to 4k so far (900 initial investigations, new 3 port valve, air release valve, more diagnostics, 2.2k on new boiler and installation, further 900 ish on conversion to sealed system, new pump fitted, another new pump (bigger)) etc. etc. etc....

It's been "broken" for two years, hence I thought I would see if people had any ideas, just might have unearthed something. And it is clear it is a flow problem, needs a heating engineer to come and look again. Darn it.

 

[sammathias]

You had 2 plumbers out, one being the one who installed boiler...then you payed £900 to seal the system which judging by the pictures would have cost next to nothing for materials. I cant see how you have had so many incompetent people to look at it. Things just don't add up. I'm starting to think it's not even a legal install. Did the veissmann engineer not even bat an eyelid over the shoddy pipework/installation?

 

[fixitflav]

His suggestion, get the boiler powerflushed, or just heat exchanger removed and cleaned fully.

Sounds like the original powerflush was done after the new boiler was installed, if it's suspected that the powerflush drove muck into the h/ex. But I'm still puzzled why the flow was low enough to give those symptoms with the original boiler. I don't think we can rule out yet the blockage being elsewhere in the system.
Also if powerflushing is going to shift it, I wonder why on the original powerflush the muck wasn't swept through the h/ex and discharged.
I had a similar problem a few years back after powerflushing, I didn't know at the time not to powerflush through the boiler. We live and learn! No obvious flow problem, but very noisy (there were other issues which didn't help - gas pressure too high, and pump output down due to clogged impeller). I cured it by chemical cleaning, just through the boiler and HW cylinder, to make sure the boiler got the full benefit.