Hi, I have a Vaillant VCW GB 221 and am having problems, the DHW it's too hot. The DHW always used to be on the cooler side even with the dial on the water valve turned to maximum but recently the water has been scalding from the taps. The boiler had a new NTC sensor and safety switch fitted but this has made no difference. I have checked the water rate and it is around 10 litres per minute, I have no way of checking my gas usage as I am on bottled gas. Your help would be greatly appreciated, many thanks Marc
Vaillant VCW GB 221 DHW is too hot
- Thread starter marctheg
- Start date
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If the flow rate is 10 li/min then it should raise the water about 35 C.
Starting at 13 C incoming at this time of year then thats 48 C. Too hot to keep your hands under for long.
What are your incoming and outlet water temperatures?
But the boiler operation depends on the gas settings!
If you dont get the boiler serviced or employ a gas registered engineer then how do you expect it to be working correctly?
Tony
Starting at 13 C incoming at this time of year then thats 48 C. Too hot to keep your hands under for long.
What are your incoming and outlet water temperatures?
But the boiler operation depends on the gas settings!
If you dont get the boiler serviced or employ a gas registered engineer then how do you expect it to be working correctly?
Tony
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This is only a 22kw boiler and does approx 7 l/min. If you have very hot water on a VCW 221 on LPG, the LPG supply governor is faulty and needs to be checked ASAP by a Gas Safe LPG engineer.
Hi, the boiler has been serviced in the last month by BG and a new NTC sensor and safety switch fitted because of the problem, but it seems like this guy is just going to change parts until he finds the fault, he has mentioned a new water valve as mine is showing signs of age with scale on the outside but the dial moves perfectly. I'll borrow a thermometer from work and measure the temperatures as you suggested and post the results up tomorrow evening, I'll also look for a more reliable engineer in my area. Regards Marc
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Do you think he made the checks on the gas settings?
Surprisingly many BG guys are not very good at doing all the gas checks, many just measure the maximum and not the minimum or even check that the circuit makes it modulate.
Many just change a part or two to get out quickly.
Tony
Surprisingly many BG guys are not very good at doing all the gas checks, many just measure the maximum and not the minimum or even check that the circuit makes it modulate.
Many just change a part or two to get out quickly.
Tony
"Quickly" your not wrong there Tony, the service was 30 minutes and involved a lot of hoovering and the parts were another visit 20 minutes in and out. I don't know what he checked, perhaps I should ask for a service schedule like I get for my car. I've checked the outflow temperature with the wifes jam thermometer (not very scientific I know) and the temperature is around 70C the incoming temperature is probably around 10 - 15C (as you said). A friend has recommended a local independent engineer and I'll give him a ring in the next day or two but it would still be good to have some background knowledge so I don't get baffled by bu....it again. I don't mind paying to have it fixed but lets be honest any monkey can change parts the skill of the job is to diagnose problems or am I expecting too much!
The skill is in the diagnosing.
BG dont seem to teach that and rely on a laptop giving common faults on each model.
Their pressure is to do so many jobs a day. That often means replacing something on a try it and see.
30 min is plenty of time to do the tests but its a matter of knowing how to test it and what to test.
An independent is usually expected to only charge for the part actually required and so will normally spend more time to do the diagnosis correctly. Otherwise it would be expensive for him buying parts not needed.
Tony
BG dont seem to teach that and rely on a laptop giving common faults on each model.
Their pressure is to do so many jobs a day. That often means replacing something on a try it and see.
30 min is plenty of time to do the tests but its a matter of knowing how to test it and what to test.
An independent is usually expected to only charge for the part actually required and so will normally spend more time to do the diagnosis correctly. Otherwise it would be expensive for him buying parts not needed.
Tony
Tonys quote:-BG dont seem to teach that and rely on a laptop giving common faults on each model.
Completely wrong on both counts. BG do teach diagnostics and the laptop is another tool to use during the diagnostic process.
Completely wrong on both counts. BG do teach diagnostics and the laptop is another tool to use during the diagnostic process.
Then why do we read on here and some of us encounter situations where BG have not been able to diagnose faults after many visits?
I once managed to assist them just over the phone ( it was a cold wet day and I did not much want to go out on a joint visit ) after they had made 45 visits without being able to find the fault.
I once managed to assist them just over the phone ( it was a cold wet day and I did not much want to go out on a joint visit ) after they had made 45 visits without being able to find the fault.
U won't get 70c on a 221 mate there is a dhw overheat stat on the dhw ht exch that will stop that, an as 831 said if your gettin 10l/m an it's to hot it's massively over gassed these models r known for it get bg back pronto!
Must have flames shooting out the flue terminal
but as previously mentioned proper gas chacks should have been carried out by B.G (pull the other it plays jingle bells).
proper independents will check to protect themselves,
1. inlet gas pressure
2. maximum boiler burning pressure
3. minimum boiler burning pressure
4. gas rate as read at meter.
only if all four of these are correct can you be satisfied the boiler is ok at a service. (along with other basic checks)
proper independents will check to protect themselves,
1. inlet gas pressure
2. maximum boiler burning pressure
3. minimum boiler burning pressure
4. gas rate as read at meter.
only if all four of these are correct can you be satisfied the boiler is ok at a service. (along with other basic checks)
Thanks for all the advice guys. I've checked the temperature now with an accurate thermometer;
Mains water straight from the tap is 9C
Running the hot tap at 8 litres/minute the temperature peaked at 59C
Is this normal?
Regards Marc
Mains water straight from the tap is 9C
Running the hot tap at 8 litres/minute the temperature peaked at 59C
Is this normal?
Regards Marc
45 degree rise at 7l/m is the makers spec so not far away maybe only a little over gassed get it checked....
Thanks for your advice fellas, I've got a slightly better understanding of my old boiler now, hopefully I won't get ripped off again.
I've arranged for the independent engineer to come and have a look next week. If I need any more help I know where to come.
Regards Marc
I've arranged for the independent engineer to come and have a look next week. If I need any more help I know where to come.
Regards Marc
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