OSO 20 RD no hot water after turning water on/off

[npaisnel]

Hi all.
I am wondering if anyone can give me advice on how to get some hot water again on a OSO 20RD water heater.
I have been away on holiday for 3 weeks, so due to the forecast snow etc, before I went away, I turned off the mains water and all power to the tank (Standard power and E7 power).

Before my return a friend turned the water and power back on, and we had hot water on our return. All working normally.

There are three taps in the cupboard near the tank. Mains cold water in, Hot water out and cold water to the house.

She who must be obeyed wants a bidet shower head unit fitted near the toilet, so, I wanted to confirm the taps near the tank isolated all taps in the bathroom.

This is what caused the problem:
With the hot tap in the bath running, I turned off the hot water 'out' on the 20 RD. As expected, the hot water went off. But when I turned the water on again on the tank the water in the bath came back on with reduced pressure. The other hot water tap in the kitchen and bathroom sink are both OK, full pressure. From reading a thread on this site and Page 4 of the Manual I tried the procedure to re charge the airgap.
Opening the commissioning valve only produced maybe half a gallon of water or less and turning the T&P relief valve allowed a small trickle of water out, you could hear air sucking back in through the tundish to allow the water out. to drain all the water out the tank to that level would have taken all night, so i gave up and turned water and electric back on.

This morning, same full flow from kitchen and bathroom sink tap, and half flow from bath tap, but all cold, even though electric is on.

Is there maybe an airlock on the bath hot feed pipe? and how do i clear that and get the hot water working again.

Neil

 

[npaisnel]

Well I have drained the complete system and re filled as per the instructions that came with the hot water tank, two of the three taps in the house produce full pressure water from the hot water tank, but the tap at the bath only produces a trickle of water.

When I first turned on the hot taps, there was water/air coming out in bursts as the air cleared, but now just a low smooth trickle of water.
I thought maybe a problem with the tap valve washer, but no, there is no washer it is a combined mixer tap shower valve, with a quarter turn gate type valve.

So it must be an air lock in the pipe between tank and bath. Have left it running for half an hour, but it is not clearing.

How do i clear this? Do I perhaps need to force water back up the hot tap from the cold tap? forcing the air backwards ?


Neil

 

[npaisnel]

Well I got it sorted, it was not an airlock. Itried forcing water back through from cold tap to hot tap but this did not work on the bath tap, although this did work on the bathroom sink and kitchen sink. It turns out the bathroom mixer taps have one way valves in for the thermo mixer unit.

Problem was limescale flakes caught in the strainers in the tap fittings, just after the flexi hoses.