Hot water fails to continue to arrive...

[Maurice]

In the bungalow we moved into last month there is an indirect cold water system, a Brink warm-air central heating system, and a HW tank fitted with 2 immersion heaters which supply all the property's hot water via a Stuart Turner 'Monsoon Standard 3.0 bar Twin' shower pump pumping both cold and hot water to their respective taps in bathrooms etc. (One of the bathrooms is in a 1st-floor extension).

All worked well for a month until we went away over Xmas, when we turned the master stopcock off under the kitchen sink. On our return yesterday it was a nasty shock to discover that the flow of water out of any HW tap soon dwindled to a trickle, then stopped. (Though if turned on soon afterwards the same sequence would occur.) The water *does* start getting hotter.

N.B. The 1st HW tap to be turned on coughed up some brownish water before changing to clear. No problem with any *cold* water tap. So am baffled because:

(1) As it happily pumps cold water the pump itself is presumably OK. (2) Why would turning the rising main stopcock off affect pumping from a tank supplying both cold & hot taps? Just a co-incidence?

(3) The pump was replaced* 4 months ago. What might the cause be of failure to pump to HW taps ?

(* Have emailed the company, it being Sunday today.)

In the meantime, it's cold washes all round.,.

[Dave Liquorice]

Well the cold end of it is. Doesn't mean the hot end is, the impellor could have disintegrated.

Is there water in the header tank? Stuck in off position ball valve, could explain air and mucky water coming out of the hot.

With the some flow then stop I suspect an air lock, make sure the header tank is full then turn on all the hot taps full pelt. Think I'd start with the pump unpowered and the nearest HW tap to the pump/cylinder and work away. If that didn't work start at the furthest and work towards.

Gawd, don't you have a kettle or pans to cook food in?

Links back to the thread about how people expect everything to be done for them when the routine or a service is broken. No pre-planning, no backup, no abilty to think of work arounds.

At this point I guess I better post a warning that if you do use hot water from a kettle or pan it is likely to be considerablly hotter than that from your taps and pose a serious scald hazard. The elven safety would say don't do it as it's unsafe and dangerous.

[Maurice]

Yes, just been up there. Water level is about 2" beneath overflow outlet.Is a big tank

Will give that a try. (Already tried leaving HW taps open and - in kitchen - opening HW tap, jamming the mixer outlet to try to force cold back into HW pipe, but didn't seem to work. Is there perhaps a flap that prevents reverse flow into HW pipe there?)

Yes, indeed, but I meant cold sluicing under the shower!

Many thanks for the response, Dave!

[Maurice]

Another puzzle. The only electrical connection I can see from the pump is to a switched fuse box labelled "5A fuse", but whether or not the switch is 'on' or 'off':

- Water still come out of the cold taps - Another connection to that fuse box is from a towel rail heater, and that works even if the that fuse box is 'on' or 'off'! Tried the other suggestion: open all HW taps fully. No change, though I notice the bath HW tap just keeps on dribbling (i.e. does not stop.

As a stopgap, we may be able to get enough seconds of HW through the powerrshower to get a good wet and rinse before the water starts to fade away.

[Fredxxx]

Isn't this mains pressure?

I'm wondering what causes the pump to run?

I'm assuming the cold side is at mains pressure, if so, if there's a drop in pump cold side, will the pump run continuously, perhaps overheating the pump motor if the master stop-c*ck is turned off?

Are you certain the pump runs with the cold tap open?

[Dave Liquorice]

Probaly at mains pressure and able to make it's way through the pump.

Towel rail feed taken before the switch in the switched fused connection unit.

Checked the header tank for water yet? Checked that the header tank ball valve works properly?

So no kettle/pans or a flannel? You don't need more than two half buckets of water for a good complete wash down. One half bucket to wet and soap, the other half bucket to rinse. Two quarter buckets is more than enough for a reasonable wash.

[Dave Liquorice]

Ah, hadn't read this when I just posted.

No crud visible blocking outlet pipe? (straw grabbing)

Well don't use the shower! Apart from somewhere to splash about with a bucket containing water heated by the kettle or hob and a flannel.

[Tim+]

Hmm, as Dave has said, it could be a failed impeller. Another thought that's crossed my mind is blockage of the cold water feed to your HW tank. Our house was built at the time when copper prices rocketed and a lot of the pipework was stainless steel (of very dubious quality). Mostly it was okay but the cold feed to the HW tank suffered a lot of internal corrosion, I think due to heat being conducted back up the cold feed to some degree when hot water wasn't being consumed. As this water is relatively well oxygenated, the corrosion here was much worse than anywhere else in the system.

Other thoughts, does the pump start when you turn on the hot tap? How about if you turn on both, does the hot flow improve? If it doesn't come on this could be a failed flow switch or just secondary to poor flow caused by pipe corrosion or an air lock.

Tim

[bert]

In message , Maurice writes

I've had a similar problem in two different houses. First time problem solved by back flushing feed from header tank to hot water cylinder. 2nd time I couldn't solve it and had to call in plumber. He eventually cleared it but more or less same method. He reckoned cause is often something lying in the tank possibly for years eventually getting into the feed pipe and blocking it.

[chris French]

It doesn't always work, possibly just because of the amount of water that needs pushing back up the pipe.

I had to do this a couple of time recently after draining down the HW system for modifications. One time I connected an old washing machine hose across the hot and cold supplies to the washing machine.

Second time I disconnected the isolation vales under the bathroom handbasin from the pipes to the taps and connected the two pipes together with a bit of plastic pipe, a couple of compression nuts and olives

[harryagain]

It sounds like the pump isn't running as required. Usually there is a pressure/flow switch to start the pump when a tap is opened. It would need two, one on hot supply one on cold. The hot one may be faulty. These pumps BTW are not supposed to be directly connected to the mains water. Are you sure the cold water IS pumped? There is supposed to be s a cold water tank filled from the mains & the pump is connected to this. It might be the same tank as you hot water supply or maybe not.

However, it's not good to be drinking from tank water as the chlorine level will be down (bugs problems).

What you really need is for your cold water mains pipe to be fixed. Likely new pipe needed, old one crudded up.

[Tim+]

Why would anyone fit a second header tank? Normal method is to fit a second outlet to the main header tank with the CW draw off lower than the one that supplies the HW tank.

It's possible though that he may be mistaken about all the CW being pumped. I suspect all HW is pumped but pumped CW goes to shower/bath only (or anything that needs a balanced supply).

Tim

[chris French]

To increase capacity? a pumped shower will use more water than a gravity shower. There may already have been more than one cold water cistern to greater cold water storage if one was a bit small.. There are 3 cisterns in our loft (pre dating us) storing about 1000L of water.

Well I assume that the kitchen cold supply is on the mains I read it as meaning the rest of the CW supply.

[Brian Gaff]

I'd be a bit worried about the dirty water and exactly how air might have got in. It might e be there is a leak somewhere if the system was left for a time, it would only need to be small.

Pumped systems can be a pain in the neck as merely stopping the pump, can just block the pipe where the impeller is. I doubt its a pump issue if they were changed recently. Brian

[Dave Liquorice]

15 years here hasn't done us any harm. And that includes the period from when we moved in to maybe a year later when I cleaned the tanks out of various dead insect life, rocks, brick dust, a dead mouse and replaced the sagging bits of ply and plastic sheet "covers" with proper fitted lids.

[Maurice]

But it is an *indirect* cold water system, so all taps (except kitchen sink) are fed from the header tank, so no mains pressure.

[Maurice]

But it probably moved the air lock on a bit, because last night I got some air out of the upstairs HW tap, and today the system seems to be working normally (able to run a hot bath).

How did the air get in there? Well, the violent wind a week ago blew the tops off 2 garden lamp posts, and blew the boiler's pilot light out. So perhaps it somehow got into the venting system...

Many thanks for all suggestions - much appreciated!

[ARW]

Your stop tap was turned off and something/someone caused the water in the cold tank to empty.

[Maurice]

But in that case that would also affect the supply to *cold* water taps, would it not? (Ths is an *indirect* cold water system, i.e. all cold taps (except kitchen sink) are fed from the same header tank as feeds the HW cylinder and then HW taps.)

[ARW]

Not if the cold water pipes were not emptied. Dripping hot tap somewhere?