linea 28

[tedsvokera]

hi there
hope someone can shed some light on my problem. i drained my hot water system to fit new bathroom suite, when i filled the system back up the boiler will only go to 41 degrees on the display and it stays at this constantly. the heating is working perfectly the hot water pressure is as normal any help would be greatly appreciated. boiler about 6 yrs old and was working perfectly prior to draining the domestic hot water system.

Eddie

 

[i_am_fubar]

Check you didn't catch your thermostat and turn the HW temp down.

 

[tedsvokera]

no ive checked that the temp is up as high as it will go on the control panel

eddie

 

[DP]

Boiler may have been set (incorrectly) to allow specific flowrate through the boiler by positioning of the inlet valve. Having restored to full flow (as it should be) water should be metered by internal component. If this is missing, or gas line is undersized, along with colder cold water, cumulative effect is lack of temperature rise.

If boiler is supplied with correct gas pressure, it will raise the cold water temperature by 35 degrees C provided specific amount of water flows through it (in your case about 10.5l per minute). Greater flow means lower temperature rise. Not enough gas (say gas line is 15mm/ undersized) same result.

If the boiler only shows 40 on the digi display, cold water would have to be 5 degrees C- not possible just now even if you live in Scotland.

 

[tedsvokera]

i only turned the stopcock off under the kitchen sink, drained through the taps then re-filled the system thats when the problem started. could it be the domestic heat exchanger or some kind of sensor
many thanks
eddie

 

[stumpydick]

When you are running hot water, does burner go off and then relight quickly? if it does, wait untill burner goes off, and close tap, the display will then show the primary temp of boiler, if above 85 deg C, the dhw heat exchanger is scaled or the primary side blocked. The burner is being shut down by hi limit stat [self resetting]

 

[Agile]

You say the DHW knob is at max!

Does the temp indicated fall if its turned to min?

If it did not change then can you guess why not?

Also turn off the DHW in to the boiler, black lever knob at right to horizontal. When thats off does any water come out of any hot tap?

If it did do you know why?

Tony

 

[tedsvokera]

You say the DHW knob is at max!

Does the temp indicated fall if its turned to min?

If it did not change then can you guess why not?

Also turn off the DHW in to the boiler, black lever knob at right to horizontal. When thats off does any water come out of any hot tap?

If it did do you know why?

Tony

tony the temp goes down if i turn the control knob down.

if i turn the hot tap on full the temp only goes to 41 degrees at the most but if i slow the flow out of the tap the temp goes up to 47 dregrees? it seemed to be working fine last night then today its playing up again. could it be the diverter valve/ motor? i am ready to throw it out the window if it wasnt so heavy!!!

if i turn the black lever to horizontal the water stops and the temp gauge rises to 61 degrees so not sure if its a limescale problem

many thanks eddie

 

[Agile]

Well that indicates that the knob shaft and the hot water pipework are both fine.

What is not indicated is the gas valve settings. I would be measuring all the various operating parameters!

By chance I went to a boiler today in SoHo which had a maximum DHW temp of about 28°C. That was quickly traced to an emergency control valve which had been mostly closed in the basement!

Sounds to me as if you may need a competent CORGI.

Tony

 

[tedsvokera]

thanks tony i would say yes to the gas readings etc but i have never touched the boiler, my main stop valve is downstairs under the sink all i done was switch it off, drain the DHW, blank 2 pipes in my bathroom then refill the system, then there was the problem, could there be a bit of crap stuck in the diverter valve or faulty thermistor?
many thanks

eddie

 

[tedsvokera]

problem solved. diverter valve service kit
best news all week. thanks for all your help
eddie

 

[tedsvokera]

problem solved. diverter valve service kit
best news all week. thanks for all your help
eddie

spoke too soon. when the central heating is off and i turn the hot tap on, the central heating flow pipe heats up?

in the service kit there was a black diaphram type bit of rubber about 40mm diameter, anyone know where it goes?

what is the maximun temp i would expect to see on the digital display for the DHW?

many thanks again

Eddie

 

[Agile]

It sounds as if the actuator is not moving or the diverter valve is stuck.

Yours works backwards with the pin pushed for DHW ! Try it manually.

The small diaphragm is used in the system flow switch but thats not fitted to all Linea boilers. There can be a system pressure switch instead.

Tony

 

[tedsvokera]

It sounds as if the actuator is not moving or the diverter valve is stuck.

Yours works backwards with the pin pushed for DHW ! Try it manually.

The small diaphragm is used in the system flow switch but thats not fitted to all Linea boilers. There can be a system pressure switch instead.

Tony

the motor is working fine but if the temp only goes up to 41 degrees (sometimes) and i remove the motor, push the push rod in and out three or four times then refit the motor the temp goes up to 48 degrees no problem
if i restrict the flow of the hot tap the temp goes up to 58 degrees

Eddie