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Combi Boiler where are the sensors
- Thread starter steph57
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Inside the
there is a mechanism. I doubt it would be a Doppler effect flow sensor in a cheap to produce domestic boiler but Doppler sensors do have the advantage of having no moving parts and can be extremely accurate. So turbine, paddle or a diaphram sensing pressure differential across a constriction or something else.
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FFS How many more times...........It's a fookin on /off switch that directly puts mains voltage onto the relay actuating coil !!! "Sika" ones were a paddle !
I have not had reason to remove a Greenstar variant but it is still on/off.
Bernardgreen stop digging , as usual you are typing absolute drivel, just give up you are not helping the OP in any way
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Hello,
Yes our new tap has flexi hose connections so maybe this is the problem? At full throttle this hot tap delivers 15 litres per minute but we would not generally turn it on that much, at the normal operating position it delivers 5 litres per minute. So maybe this tap is at the end of the run and at partial turn on does not give enough flow to kick start the boiler into operation?
The main question was whether we should be looking for any sensors in the hot water pipework? but it appears not and that all sensors are within the boiler itself.
So thank you for your comments we will try turning on the utility sink the full amount to initiate boiler fire, if that fails we will use the kitchen tap to kick start the boiler, not a huge problem, just an intriguing puzzle.
Yes our new tap has flexi hose connections so maybe this is the problem? At full throttle this hot tap delivers 15 litres per minute but we would not generally turn it on that much, at the normal operating position it delivers 5 litres per minute. So maybe this tap is at the end of the run and at partial turn on does not give enough flow to kick start the boiler into operation?
The main question was whether we should be looking for any sensors in the hot water pipework? but it appears not and that all sensors are within the boiler itself.
So thank you for your comments we will try turning on the utility sink the full amount to initiate boiler fire, if that fails we will use the kitchen tap to kick start the boiler, not a huge problem, just an intriguing puzzle.
I think you are pretty close here....flow switches do have a tolerance when operating ( so they don't fire the burner due to a dribble etc) and probably yours is on the wrong side of that tolerance.
Try turning the hot tap on fully and quickly and I bet the boiler fires up.
John
Try turning the hot tap on fully and quickly and I bet the boiler fires up.
John
The man's a bloody liability - he's sloped off from the UFH thread now he's been proven yet again to be totally clueless.
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Have a heart Dan ....Bernard possibly lives on his own with DIYnot being his only outlet...
Stop bursting his bubble..
Stop bursting his bubble..
I have already told you what to do above.
The boiler has no idea where the DHW is going to.
All it responds to is the flow rate!
I have also told you about the advanced test for a crossover!
Tony
We have different opinions, neither of us is clueless, but we do have different motivations behind our opinions. We also have different sources of information and experience. You will never convince me and I woll never convince you. I walk, I do not slope
I choose to live alone,. but I am far from being lonely. DIYnot is an amusing distraction from the more serious things in life,
Hello again,
We tried the system this morning from cold, turned the boiler on to hot water operation then ran the utility hot tap at 15 litres per minute for quite some while but the boiler failed to fire. We then went in the kitchen turned on the kitchen hot tap a bit, bingo the boiler fires up and we then get hot water out of the hot water tap in the utility room, even though that tap failed to start up the boiler.
We looked at the crossover test suggested in one of the posts but could see no way of turning off the mains water feed to the boiler? the cold water supply pipe coming into the boiler has a double check valve but no isolation valve, so unless there is some sort of tap inside the boiler itself the only way of shutting down the mains supply to the boiler is to turn off the mains stopcock, which would of course defeat the whole object of the exercise by shutting everything down!
Our mains water pressure is very high I cannot remember exactly but 8 or 9 bars comes to mind? certainly when the plumber fitted our new electric shower he did a pressure test and had to fit a pressure check valve in the supply pipe to ensure the shower worked OK without any damage.
Anyway our conclusion is that we need to operate the kitchen hot water tap in order to fire up the boiler but that when fired we can then get hot water out of the utility room hot tap! A rather quirky sort of hot water system but we cannot afford to get a plumber or heating engineer out just to check this issue when we can learn to live with it for now. We will need to change a radiator and get the boiler serviced in the spring and so we will mention this hot water issue when our plumber comes to do those jobs.
This is our first experience of a combi-boiler and they do seem much more quirky and temperamental than old fashioned systems and whilst they might save energy, they seem seem to waste of lot of water each time you turn the tap on and have to run water through the system to get the boiler to fire up.
We tried the system this morning from cold, turned the boiler on to hot water operation then ran the utility hot tap at 15 litres per minute for quite some while but the boiler failed to fire. We then went in the kitchen turned on the kitchen hot tap a bit, bingo the boiler fires up and we then get hot water out of the hot water tap in the utility room, even though that tap failed to start up the boiler.
We looked at the crossover test suggested in one of the posts but could see no way of turning off the mains water feed to the boiler? the cold water supply pipe coming into the boiler has a double check valve but no isolation valve, so unless there is some sort of tap inside the boiler itself the only way of shutting down the mains supply to the boiler is to turn off the mains stopcock, which would of course defeat the whole object of the exercise by shutting everything down!
Our mains water pressure is very high I cannot remember exactly but 8 or 9 bars comes to mind? certainly when the plumber fitted our new electric shower he did a pressure test and had to fit a pressure check valve in the supply pipe to ensure the shower worked OK without any damage.
Anyway our conclusion is that we need to operate the kitchen hot water tap in order to fire up the boiler but that when fired we can then get hot water out of the utility room hot tap! A rather quirky sort of hot water system but we cannot afford to get a plumber or heating engineer out just to check this issue when we can learn to live with it for now. We will need to change a radiator and get the boiler serviced in the spring and so we will mention this hot water issue when our plumber comes to do those jobs.
This is our first experience of a combi-boiler and they do seem much more quirky and temperamental than old fashioned systems and whilst they might save energy, they seem seem to waste of lot of water each time you turn the tap on and have to run water through the system to get the boiler to fire up.
If you have 8 bars of mains pressure I'd be very wary of those Flexi hoses.
My thoughts too is its crossflow. Get chap to fit non return valves to the new taps.
Also consider a pressure reducing valve on the main to the house.
My thoughts too is its crossflow. Get chap to fit non return valves to the new taps.
Also consider a pressure reducing valve on the main to the house.
Not a problem if your water supply is not metered but if the customers is on a metered water supply then the cost of wasted water has to be included in the overall cost ( savings ? ) of a combi installation.
These may be from the wrong manual. The manual is a public domain document
THESE INSTRUCTIONS APPLY TO UK MODELS ONLY
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE APPLIANCE
Which suggests the flow switch operates on pressure or pressure fluctuations due to very small amoumts of flow as the air trapped in hot side pipe work is compressed by the water hammer of the cold tap shutting off.
If the flow switch is a pressure ( differential ) operated device and the mains pressure is as high as quoted then possibly the switch is unable to detect the comparatively small change in pressure due to the tap close to the boiler. ( small percentage change ) Pressure reduction valve on the incoming mains may be needed.
The OP asked where the flow switch is located.
THESE INSTRUCTIONS APPLY TO UK MODELS ONLY
THESE INSTRUCTIONS ARE TO BE LEFT WITH THE APPLIANCE
Which suggests the flow switch operates on pressure or pressure fluctuations due to very small amoumts of flow as the air trapped in hot side pipe work is compressed by the water hammer of the cold tap shutting off.
If the flow switch is a pressure ( differential ) operated device and the mains pressure is as high as quoted then possibly the switch is unable to detect the comparatively small change in pressure due to the tap close to the boiler. ( small percentage change ) Pressure reduction valve on the incoming mains may be needed.
The OP asked where the flow switch is located.
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