Am i missing something?

[Neil T]

A customer has h/w problem. Whenever h/w is run on the first floor it runs to a trickle and that is with one tap open.
It's a large 15 yr old house with 3 baths, shower room and 5 toilets with basins. The loft has been converted and has its own shower room run from its own boiler and no issue with that.
The system is run by 2 potterton 80 boilers and megaflo cylinder which seems to be sufficient for the outlets. There was a grundfos 15 50 pump before the h/w inlet on the cylinder which we thought to be faulty. I've changed that to an alpha2 25 60 and put new pump valves on too as one wasn't shutting properly. Problem is still there and new pump is showing max flow through it at 0.3m[SUP]3[/SUP]/hrs when tap running and 0.1m[SUP]3[/SUP]/hr when idle.
Also, the expansion vessel is at 2 bar. There is h/w coming from cylinder but obviously not enough. As the thread says, i may be missing something so any help/advice would be appreciated.
I've attached some pics of the pipework around cylinder.
Thanks

 

[SimonG]

Cleaned out the strainer on the combi valve?

 

[Chalked]

This is why you need to be G3 registered.
The heating pump has nothing to do with hot water flow rate and the expansion vessel is on the heating, so will have nothing to do with it either.
Not having a go, but you need to be trained in how these cylinders work to successfully fault find.
Regards.

 

[Riley]

Are you G3 mate

 

[Billy Bob Bob]

just to clarify,you changed the 15 50 grundfos ch pump?????????

 

[Chalked]

Just had a better look at your pics. That pump is on the secondary circuit, so needs to be bronze or stainless steel. If that's a normal heating pump, they will not only be getting a poor flow rate of hot water, it will be going rusty too.

 

[finchy01]

G3 / unvented engineer needed my friend. You have already been given the most likely remedy but do yourself a favor and get one of us in. These things can literally blow up if not done right.

 

[Stigster]

Just had a better look at your pics. That pump is on the secondary circuit, so needs to be bronze or stainless steel. If that's a normal heating pump, they will not only be getting a poor flow rate of hot water, it will be going rusty too.

The most costly damage I have ever seen was on a property that had a CH circulating pump instead of a bronze pump on the secondary return. They left it all running when they went on holiday, the pump literally fell in half from corrosion and caused a mega flood. It was a huge expensive property full of oil paintings, expensive carpets, books and antiques. They had water running from the loft at mains pressure and flow rates. Definitely use the right kind of pump!

 

[tolly]

As said, pump is only for secondary so should be bronze or stainless, fit a ups15-50n or a dab bronze pump, i dont like the wilo sb30 bronze pumps, they dont seem to last long.

Quite worrying you didnt spot this straight away as this is basic stuff, it has nothing to do with dhw flow rates at the outlets,l.

 

[Neil T]

Thanks for the input guys. I dont touch unvented or gas as im not reg'd but as i thought pump was faulty i assumed i was within regs to change it.
If there is someone with certs in the northwich, cheshire area, pm me and we can make some arrangements.
Cheers

 

[Neil T]

I tend to steer clear from boiler/cylinder work apart from rad work or pumps and stick to bathroom installs and other run of the mill stuff, that's why ask for help on here if there is something I'm unsure about. Just thought I'd better add that as a foot note

 

[finchy01]

Fair answer. You know a lot of stuff about bathrooms that I don't I'm sure. But that's why I draw the line at changing a tap or mastic. Full refits etc I call the likes of you. My advice (although it sounds like you are already) is to do the same with gas and unvented.

 

[Neil T]

I sub out all my gas work to someone locally and he throws work my way. Dont know anyone locally who does unvented so i generally tell customers to search for someone whos got certs

 

[Neil T]

Update: job sorted. Unvented engineer found that mixer valve had failed on cylinder and also pointed out that installers hadn't fitted a low level tundish so sorted that too. I replaced the pump back to the original 15 50 (bronze) on the secondary circuit as it had failed as I suspected. The hw is now perfect and 3 happy people: customer, me cos I got the help customer needed and unvented engineer as he now has the nod for any work regarding the system plus servicing