Quizzes & Puzzles0 min ago
Vailant boiler no hot water
39 Answers
We have intermittent hot water. The taps run warm (not hot) for a few secs then ice cold then warm then cold etc. The following have been replaced: sensor, heat exchanger, and a small pipe to the "bladder". Today theplumber is replacing diverted valve. If this doesn't work any other ideas?! ! The boiler is not showing a fault code.
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Cause:
1. When tap opened - Noticed no demand lights (Green & yellow lights both off).
2. Managed to borrow manuals from family friends who have the same boiler/manuals. Checked diagnostics info, i & + = d.22 = 0 when hot tap open (should be 1 to confirm water demand)
Action:
1. On water incoming to boiler (after water service valve) there is an aqua sensor assembly, which was not detecting water flowing through boiler when hot tap is opened, hence no hot water, boiler = demand not present. So the cold mains water passed straight through boiler and out of hot water tap.
2. Isolated power, Closed all service valves, depressurised system.
3. Removed circlip on aqua sensor
4. Removed propeller and cleaned - contained a bit of grit.
5. Removed the breather nut on top of aqua sensor housing, which was blocked - cleaned and blew through it to ensure it was open.
6. Refitted in reverse order.
7. Refilled boiler.
8. Opened service valves
9. Power ON - Opened Hot water tap, green light flashing & yellow on = Hot water!!!!!!
Aqua sensor is in two parts,
The operational principle I understood as follows:
- the reciever (RX) the sensor (fitted on outside of housing and has three wires)
- propellar - the transmitter - as water flows through the housing the propeller spins, and produces an oscillating signal which is picked-up by the RX, the faster the propellor spins the higher the frequency and the greater the demand for hot water.
As the propellor was not spinning before, there was no demand, hence the cold water.
1. When tap opened - Noticed no demand lights (Green & yellow lights both off).
2. Managed to borrow manuals from family friends who have the same boiler/manuals. Checked diagnostics info, i & + = d.22 = 0 when hot tap open (should be 1 to confirm water demand)
Action:
1. On water incoming to boiler (after water service valve) there is an aqua sensor assembly, which was not detecting water flowing through boiler when hot tap is opened, hence no hot water, boiler = demand not present. So the cold mains water passed straight through boiler and out of hot water tap.
2. Isolated power, Closed all service valves, depressurised system.
3. Removed circlip on aqua sensor
4. Removed propeller and cleaned - contained a bit of grit.
5. Removed the breather nut on top of aqua sensor housing, which was blocked - cleaned and blew through it to ensure it was open.
6. Refitted in reverse order.
7. Refilled boiler.
8. Opened service valves
9. Power ON - Opened Hot water tap, green light flashing & yellow on = Hot water!!!!!!
Aqua sensor is in two parts,
The operational principle I understood as follows:
- the reciever (RX) the sensor (fitted on outside of housing and has three wires)
- propellar - the transmitter - as water flows through the housing the propeller spins, and produces an oscillating signal which is picked-up by the RX, the faster the propellor spins the higher the frequency and the greater the demand for hot water.
As the propellor was not spinning before, there was no demand, hence the cold water.
I think the sensor must spin .. and it isn't.
http://www.uk-plumbin...045e89fc42597958f0eeb
http://www.bhl.co.uk/...L_194829_AQUA_SENSOR_
http://www.heatingbit...aillant_1_1678_36.htm
http://www.uk-plumbin...045e89fc42597958f0eeb
http://www.bhl.co.uk/...L_194829_AQUA_SENSOR_
http://www.heatingbit...aillant_1_1678_36.htm
-- answer removed --
