heatline c24

[stevep]

I have a heatline c24 condensing boiler.central heating works fine at 85'c,hot water will work at 65'c,but only if i reduce cold water flow rate to 40% of mains pressure,any higher and hot water is luke warm.any idea what the fault is at the moment it takes half an hour to run a bath.
Have replaced dhw sensor,diverter valve.
Cheers

 

[wnjswozo]

sounds like incorrect gas supply to boiler,ie not piped up right,you need to gas rate or fga to rule this out.see it a lot where combis not piped up right

 

[stevep]

thanks for reply,can you explain what gas rate/fga is?
cheers

 

[newbie1]

firstly incoming pressure might be too high this leads to boiler being unable to keep up with the flow
secondly do not attempt to play with the gas yourself
you need a registered gas engineer to examine you gas supply pipe and to gas rate it
some combis are fine on 15mm supply pipe but others need 22mm you need to check the paperwork supplied with the boiler this will tell you what supply pipe is needed
this is not a diy job

 

[Kip]

Gas Rate would be the free option unless you wish to spend 700 quid on a machine which is the fga(flue gas analyser)

To Gas rate, dependent on your meter (metric is a dial of numbers) and (imperial is a rotating hand)

For metric:

Record your start reading, run your hot tap for on full for 2 minutes then record the end reading. Calculate the difference and times is by 321.

For Imperial

Time how long it take for the dial to do one full revolution and times it by 1664.

Now its been a while since ive done gas rates this way, i take the reading and look in the corgi handbook. So if ive got the calculations the wrong way round feel free to correct me.

 

[newbie1]

he wont get accurate reading because its not operating correctly as the flow rate seems wrong at 30mins to run a bath
first step is get someone to check flow rate of mains pressure and then check inlet gas pressure to see if these are correct
check incoming pipe size and length of run
it really is not a diy job too many variables

 

[stevetheplumber]

a 24kw boiler will produce about 8 litres with a 35 degree rise in a minute use a jug to time the flowand see if your getting this

 

[newbie1]

i predict next question will be what sort of jug

 

[REDSAW]

i predict next question will be what sort of jug

dont be silly,
whats a jug?.

 

[Kip]

he wont get accurate reading because its not operating correctly as the flow rate seems wrong at 30mins to run a bath
first step is get someone to check flow rate of mains pressure and then check inlet gas pressure to see if these are correct
check incoming pipe size and length of run
it really is not a diy job too many variables

Correct he wont get an accurate reading, thus pointing out the pipe sizing would be incorrect.

 

[newbie1]

he allready knows it isnt flowing the correct amount of water so gas rating it would be pointless
he needs a engineer to check pipe size/inlet pressure/burner pressure
check flow rate of incoming main as may need a reducing valve
plate heat exchanger could also be playing up
none of which are diy

 

[stevetheplumber]

he allready knows it isnt flowing the correct amount of water so gas rating it would be pointless
he needs a engineer to check pipe size/inlet pressure/burner pressure
check flow rate of incoming main as may need a reducing valve
plate heat exchanger could also be playing up
none of which are diy

setting the mains flow to the correct amount will tell him if he actually needs an engineer if he sets it to 8 litres and its making the specified temperature then theres no fault
get many people saying that their 24kw combi isnt working when all thats wrong is the inlet temp of the water has dropped in winter and the appliance is running to fast
one of the reasons i reccomend 28 kw minimum size for combis

 

[newbie1]

unless he has access to a flow cup he will struggle to gauge mains flow and as my cheap one cost best part of 50.00 prob easier to just get an engineer
i nearly crapped myself when they said 50.00 for a cup with a hole in it

 

[stevetheplumber]

firstly incoming pressure might be too high this leads to boiler being unable to keep up with the flow
secondly do not attempt to play with the gas yourself
you need a registered gas engineer to examine you gas supply pipe and to gas rate it
some combis are fine on 15mm supply pipe but others need 22mm you need to check the paperwork supplied with the boiler this will tell you what supply pipe is needed
this is not a diy job

all combis need 22mm pipe unless there sited on top of the meter wih no other gas appliances being fed
30 mins to fill a bath would depend on the size of the bath and incoming water temp

 

[stevep]

The boiler is using 22mm pipe on a 6ft run from gas meter,measured flow rate was 5 litres at temp of 50'c.
Heatline tech data is 11.86 litre at rise temp of 30'c

 

[stevetheplumber]

The boiler is using 22mm pipe on a 6ft run from gas meter,measured flow rate was 5 litres at temp of 50'c.
Heatline tech data is 11.86 litre at rise temp of 30'c

pipework sounds ok so you need to have the boiler checked for blockage in the water ways maybe a filter on inlet or heat exchanger blocked possibly divertor valve
you need to know the temp of cold water entering to get the temperature rise
you also need to check meter is delivering enough gas could be a govenor failure this you can get checked free by your gas supplier if you tell them you suspect low preasure

 

[wnjswozo]

sounds like gas supply issue ,did you not say you had to turn hot tap down ,for hot water to be at a hotter temp ,this points to gas supply anything from blocked gas vavle to govener

 

[newbie1]

def either gas valve/burner blockage or internal waterway poss plate heat exchanger as pipework size is ok
if its working fine on heating i would err towards a water blockage

 

[stevep]

I use the cold water inlet isolation valve on the boiler to reduce water flow rate to about 5 litres a minute for a temp of 50'c.
If i fully open cold water inlet isolation valve on boiler hot water temp is reduced to luke warm at best.