Hi
I've got a problem with my hot water system and, having searched through the posts and learned a lot, wondered if someone might have some incite.
I've bought a 3 storey house (built 8 years ago) with the hot water tank on the 3rd floor and cold storage tank in the loft. It's a
2 circuit system, one small cold tank for the central heating/water heating circuit and one large tank for the cold supply to the taps and the hot water cylinder.We have bathrooms on the 2nd and 3rd level and have recently fitted a shower tap in the 2nd and a power shower (using water from the hot tank) in the 3rd.
I noticed that water pressure on the 2nd floor seemed to be sometimes good, mostly bad and when we fitted the power shower it started to play up when pressure was low, sounding like it was sucking air (gets noisy and the motor seems to "rev" up). This would occur even on it's lowest power setting.
We assumed an airlock, back flushed the system, and everything was fine but over the following days you could see the pressure dropping in the middle bathroom, eventually to the point where the power shower plays up on the top floor. Every time we flush it it's prefect but the pressure slowly dies over the following days and then problems occur.
I've checked the cold water tank and it seems clear. Once the system is flushed I can leave the power shower on 9 (at which point flow is high enough that the bath starts to fill) for 5 minutes while I go up and look at the cold water. The water is going down but there's enough water going into the tank that I don't think the tank is emptying.
I've now found I can flush the system by switching water off to the hot tank and draining a few litres of hot water from the middle bathroom, then switch the water back on, you can hear the water run down the pipe, you get a couple of spurts of air when you switch the tap back on and then it all fixed. I've now got this down to a 2 minute pitstop!
I'm assuming it must be air that's restricting the flow somewhere if it can be fixed by flush/drawing water. I also assume that, although I think when the pressure is low the power shower is drawing air down the vent pipe when on power level 1, as it works fine after flushing on power level 9 for 10+ minutes it's not the presence of the power shower that causing problems. Also, as I have low pressure in both bathrooms the blockage must be in the common pipe and before it splits to the top floor bathroom.
I've yet to check which pipe water comes out of when I back flush (the vent pipe or the bottom of the water tank). Maybe it's coming out the vent pipe and I need to put my finger over it and back flush the cylinder? I'm tempted to temporarily block the vent pipe (I've seen the posts about the danger of fitting one values to the vent pipe
- I just mean for 5 minutes) and see if the power shower can draw the blockage through.
I'm wondering if the problem comes back so quickly if I'm actually fixing the problem or just moving an air bubble and then it comes back? Any other tests I should do? Many thanks
Jason