Hello
This is a problem causing scratched heads not only to me (a total non-expert when it comes to plumbing) but also to British Gas (I have HomeCare 200 cover).
Basic facts:
1. I have an indirect system.
2. On Friday morning (last day of 2010!), my cold water storage tank started to overflow through the warning pipe.
3. I turned off the ball valve to shut off the inflow to the tank.
4. The overflow continued.
5. I then noticed that steam was rising off the tank, stuck my hand in the "cold" water - and found that it was almost warm enough to take a bath in.
6. Obvious assumption: the hot water expansion pipe was venting from the hot water cylinder into the cold water tank. But it wasn't.
7. So I reached into the tank ... and discovered that hot water was flowing back up into the tank through the pipe that supplies cold water to the hot water cylinder.
8. I contacted British Gas, who sent out a Dyno-Rod engineer. (I'll cut the next stage short, as it involved Dyno-Road and BG batting the problem back-and-forth - i.e. was it a plumbing problem or a central heating problem?)
9. In the end (on Saturday) a BG engineer decided that it's all due to the thermostat on the hot water cylinder being knackered, causing the water to overheat and vent up into the cold water tank. (Though he didn't/couldn't explain why it was flowing up the cold water supply pipe rather than expansion pipe designed for the job.) Unfortunately, he didn't have a replacement thermostat, and we agreed that he would come back Wednesday morning.
10. In the meantime, the storage tank continued to overflow, even with the cold water inflow still turned off - and even with the entire heating system turned off.
11. So last thing last night, as an experiment, I drained the cold water storage tank by running the hot water taps only. Then I switched off the entire system - no heating, no hot water. This morning, the level of the tank had risen by 8 inches - of cold water!
My guess is that the heat exchanger coil in the hot water cylinder has ruptured, and that water from the heating system - whether hot or cold - is filling the cylinder and backing up into the cold water tank through the easiest available route, the cold water supply pipe. The only strike against this theory is that the water rising into the cold water tank is totally clear and sweet as a daisy - not a sign of contamination.
Any advice would be greatly appreciated!
Paul
This is a problem causing scratched heads not only to me (a total non-expert when it comes to plumbing) but also to British Gas (I have HomeCare 200 cover).
Basic facts:
1. I have an indirect system.
2. On Friday morning (last day of 2010!), my cold water storage tank started to overflow through the warning pipe.
3. I turned off the ball valve to shut off the inflow to the tank.
4. The overflow continued.
5. I then noticed that steam was rising off the tank, stuck my hand in the "cold" water - and found that it was almost warm enough to take a bath in.
6. Obvious assumption: the hot water expansion pipe was venting from the hot water cylinder into the cold water tank. But it wasn't.
7. So I reached into the tank ... and discovered that hot water was flowing back up into the tank through the pipe that supplies cold water to the hot water cylinder.
8. I contacted British Gas, who sent out a Dyno-Rod engineer. (I'll cut the next stage short, as it involved Dyno-Road and BG batting the problem back-and-forth - i.e. was it a plumbing problem or a central heating problem?)
9. In the end (on Saturday) a BG engineer decided that it's all due to the thermostat on the hot water cylinder being knackered, causing the water to overheat and vent up into the cold water tank. (Though he didn't/couldn't explain why it was flowing up the cold water supply pipe rather than expansion pipe designed for the job.) Unfortunately, he didn't have a replacement thermostat, and we agreed that he would come back Wednesday morning.
10. In the meantime, the storage tank continued to overflow, even with the cold water inflow still turned off - and even with the entire heating system turned off.
11. So last thing last night, as an experiment, I drained the cold water storage tank by running the hot water taps only. Then I switched off the entire system - no heating, no hot water. This morning, the level of the tank had risen by 8 inches - of cold water!
My guess is that the heat exchanger coil in the hot water cylinder has ruptured, and that water from the heating system - whether hot or cold - is filling the cylinder and backing up into the cold water tank through the easiest available route, the cold water supply pipe. The only strike against this theory is that the water rising into the cold water tank is totally clear and sweet as a daisy - not a sign of contamination.
Any advice would be greatly appreciated!
Paul