Hi,
I posted here a few weeks ago, but unfortunately still have the same and ongoing problem.
We recently installed a Vaillant 838 combi to replace an aged Gloworm.
When almost any appliance / tap or toilet in the house ceases to uses cold water the boiler fires for about 10 seconds to try to supply DHW.
We have now exposed 95% of all the pipework throughout the house and there are no dead legs present.
We tried a one way valve in the DWH outlet at the boiler - this made no difference whatsoever.
We currently have a one way valve at the CW inlet to the boiler. This made a slight improvement with the boiler only coming on about 8 out of 10 times after a cold water demand although it has also introduced a very noisy water hammer at the stop tap, which I will replace shortly.
We installed a Zilmet water surge stopper in the CW feed at the boiler. This made almost no difference.
We installed a full flow valve in the DHW outlet at the boiler. With this closed i.e all of the house DHW pipework disconnected the problem is still present.
I can change the hot water flow sensitivity on the boiler D88, between two settings, but on the second less sensitive setting you have to demand "lots" of DHW before it will notice a genuine demand.
Standing CW pressure at the boiler is about 3 Bar and drops to about 1 Bar with a CW tap wide open elsewhere in the house.
Any other suggestions or thoughts would be most welcome as this is driving both myself and the original installer to distraction.
Many thanks
I posted here a few weeks ago, but unfortunately still have the same and ongoing problem.
We recently installed a Vaillant 838 combi to replace an aged Gloworm.
When almost any appliance / tap or toilet in the house ceases to uses cold water the boiler fires for about 10 seconds to try to supply DHW.
We have now exposed 95% of all the pipework throughout the house and there are no dead legs present.
We tried a one way valve in the DWH outlet at the boiler - this made no difference whatsoever.
We currently have a one way valve at the CW inlet to the boiler. This made a slight improvement with the boiler only coming on about 8 out of 10 times after a cold water demand although it has also introduced a very noisy water hammer at the stop tap, which I will replace shortly.
We installed a Zilmet water surge stopper in the CW feed at the boiler. This made almost no difference.
We installed a full flow valve in the DHW outlet at the boiler. With this closed i.e all of the house DHW pipework disconnected the problem is still present.
I can change the hot water flow sensitivity on the boiler D88, between two settings, but on the second less sensitive setting you have to demand "lots" of DHW before it will notice a genuine demand.
Standing CW pressure at the boiler is about 3 Bar and drops to about 1 Bar with a CW tap wide open elsewhere in the house.
Any other suggestions or thoughts would be most welcome as this is driving both myself and the original installer to distraction.
Many thanks