Glowworm Swift Flow 75E 80E Lose of Hot Water

[Homelover]

Hi my name is Alan iam new to the site. looking for help with my Swift Flow 80E Boiler. The problem is when my Central heating is being run or has been running I can not get any Hot Water when I turn on the tap although the gas demand increases I suspected the Diverter Valve was not switching over only to find there is no Diverter Valve fitted to this Model. a quick read through the servicing Manual did not make a great deal of sense as to how the system switches between Central Heating and Domestic Hot Water. I changed Both Themistor Assemblys the Domestic and the Heating as they seemed to be the Cheapest 2 items that might be at Fault, but no change I now fear it could be the Control Board that is at fault and that looks like a more costley part ( any idea of the cost exchange unit or brand New would be helpful) any help would be appreciated . Al an

 

[kevplumb]

try just hot water ie switch heating off then see what happens

 

[Homelover]

Hi Kevplumb yes thats fine if the C/Heating has not been running for a good while and has cooled right down, Its the lack of a Diverter Valve that throws me cant get in my head how it switches Al

 

[kevplumb]

dosent switch the hot water exchanger is inside the heating exchanger
nothing wrong with the flow switch if it fires cold
whats the flowrate like ?

 

[Homelover]

Hi Kevplunb yes flow Rates Fine the pump seems fine runs on after C/heating turns off the Fan sounds Ok it has never cut out on over temp, the problem started about 6 weeks ago and got progressively worst. I have just run 2 baths tonight with no problems but there again I have not had the C/Heating On. Al

 

[kevplumb]

trying mate long time since i repaired one of these
i assume you tested the thermistors before you fitted them been caught like that before

 

[Homelover]

At £22 each I would have thought the manufacturer had tested them they were Genuine Hepworth Spares. If you wake in the middle of the night with more ideas be sure to pass them on your help is greatly appreciated, I was hopping this was a common problem that could be pinpointed with ease being a mechanic i know only to well some faults dont have a easy fix.. Al

 

[kevplumb]

only thing i can think of at the moment close the central heating isolaters
see if that works

 

[Homelover]

Thanks for that Kevplumb cant really see what thats going to prove as that will be the same as running with the C/Heating Off and has I mentioned earlier when the C/Heating is not running or as not been running for a while then the Domestic Hot water works fine. Its something not Switching Over to Domestic Hot Water when the C/Heating is being Run or has been Run and the system is still Hot or Warm. Al

 

[ChrisR]

I've never seen with this model but it appears that in HW mode, the pump is supposed to run for 30 seconds then stop, whereas it keeps going in CH mode. It seems a bit odd - that's enough for the CH pipes to get quite warm.

Going back a notch, the DHW flow switch is mounted in a pipe on the left just above the small expansion vessel (which is lemon shaped) and has 2 red wires whic go to terminal block 4 on the pcb. Isolate the boiler from the electricity mains, take out plug 4 and check for continuity with a meter across the red wires. There should be a connection when water is drawn from the hot tap, no connection otherwise.

 

[Homelover]

Hi ChrisR yes got continuity across Flow Switch Red Wires when drawing hot water nothing when Tap is OFF. So thats the Flow Switch Proved Ok any further thoughts other than get the GlowWorm Service Man In Al

 

[ChrisR]

What about the PUMP? You gotta read what we write!!

 

[Homelover]

Hi again ChrisR I see were your coming from with the pump RUN ON, the next time it Faults on me I will check to see if the pump cuts out after 30 secs when it switches to hot water demand, At the moment there is no problem with the Hot Water as the Central Heating is not and has not beed used over the past few days due to the warm weather Al