Restricted flow from hot taps via combination cylinder

[andy LL]

Good afternoon and thanks for looking.
Combination hot water cylinder cold feed valve stuck shut so header emptied. Electric Immersion heater survived and hot compartment seems full but flow to taps very limited.
Vent seems clear. No external cold feed between tanks. Seems to be integral?
Is there an overheat safety valve or is it just gunge somewhere?
Dim but willing, A

 

[townfanjon]

What type of cylinder Andy , could you post a pic .

 

[ShaunCorbs]

What type of cylinder Andy , could you post a pic .

Think it's one of those fortec cylinders

Sounds like either a blockage or air lock

Do you live in a hard water area andy ?

 

[townfanjon]

Think it's one of those fortec cylinders

Sounds like either a blockage or air lock

Do you live in a hard water area andy ?

Yep probably is a fortec type but could be thermal store .

 

[ShaunCorbs]

Yep probably is a fortec type but could be thermal store .

agree but havent seen a thermal store that takes how water from the cylinder (instead of going through the coil) and normally there mains pressure arnt they?

 

[SavageW]

Sounds more like fortic cylinder from what you have described, with what sounds like the ball valve has seized an loss of pressure at your hot taps. The immersion would still heat the water in the cylinder but has no effect to your flow rate at your hot taps. Ideally need a pic of your cylinder to help diagnose further mate

 

[townfanjon]

agree but havent seen a thermal store that takes how water from the cylinder (instead of going through the coil) and normally there mains pressure arnt they?

Yep understand your thinking , but if the header tank on a therm store emptys it wont work . We need a pic lol

 

[SavageW]

Yep understand your thinking , but if the header tank on a therm store emptys it wont work . We need a pic lol

Townfanjon - would that affect flow rates to dhw taps on a thermal store if the header tank run dry?

 

[townfanjon]

It wouldnt alter the flowrate but it wouldnt get hot water if it was a thermal store with a pump ( although a lot dont have them now ) I work a lot on the Flowmax and get loads of calls with customers saying they have no HW , I tell them how to fill the header tank and the HW comes back lol

Too many guesses on this post we need the OP to come back with a pic .

 

[andy LL]

Thanks for input so far. It's a fairly small, older, unlagged unit with obvious separation
between joined tanks. Swan neck vent in expansion tank with raised flange at its base.
No side winder just electric heated. Will get a pic up later.
Expansion tank fills OK.
If no safety gismos it must be gunge somewhere.

 

[Chalked]

Has the gate valve sheared off?

 

[andy LL]

Has the gate valve sheared off?

Strangely, no isolator for DHW that I can find. Just stop tap on cold feed to expansion tank. Irritating 'cos it also isolates DCW
Was working fine before ball valve stuck.

 

[andy LL]

Just as a courtesy for the help offered. Turned out to be simple outlet from the DHW tank clogged with boss white/lime scale so thought whoopee! After clearing and flushing still no flow??? Turned out to be on an immersion timer which must have been on override when I first arrived then reset. No one thought to mention that and it was remote from the tank. Ha, ha, lesson learned. Thanks again.