aah! Spluttering Hot Tap fed from Immersion Heater!

[LordJimimac]

Hello all!

I have just moved into a new flat in the loft of an old building that has just immersion heated hot water. This is the setup:

- The cylinder (about 1.5m tall, one heater element at the top) is in a cupboard on the landing
- The cistern is above in the roof space - it looks quite small (it is squeezed into the apex of the roof)
- The bottom of the cistern is about 1m above the top of the cylinder
- The water heats up fine
- The cold water feed to the cistern (normal size pipe) is on max and there is good pressure
- The cold water feed into the bottom of the cylinder (wider pipe) is on max

The water flow from the hot pipe keeps varying dramatically in pressure, building up very fast then dropping to a drip, then steady then high pressure again. I have no idea why this is happening (I assumed that the inflow and outflow to the cylinder and tap could be tuned to sort it but this doesn't work).

If anybody can help me I would be really grateful as I want to run a shower of the tank and cannot with this unsteady flow!

Many many thanks to anyone out there that can help!!

 

[ArtfulBodger]

I would suspect a partial blockage in your cold feed to the HWC resulting in an erratic supply.

If you have access, check to see if anything is blocking the cold feed from the inside of the cold water cistern. If you find a dead rat or something like that throw it away - you won't need it later - also you probably won't fancy a bath for quite a while.

If you find nothing, shut down the cold feed to the HWC and ensure that all of the hot taps run out. Disconnect the feed downstream of the valve (this is an important bit BTW) and hold a bucket underneath the valve and open it and note the flow. It should be heavy and consistent. On second thoughts have two buckets ready. If it is then you may have a blockage further down towards the HWC. If it isn't then you need to remove the blockage whilst the feed is disconnected. This will involve emptying the cold water cistern and shoving whatever comes handy either up or down the feed, depending on which is easiest.

On the other hand though, you may just have an air lock.

 

[steino]

1st thing to try is draining the system and then carefully refilling to rid of any possible airlocks. turn off stopcocks (prob in roofspace), drain system via taps and then turn on stopcocks slowly with taps still on to let any air be worked out as the system refills. this worked for my spluttering hot taps.

 

[LordJimimac]

Hi Steino and ArtfulBodger (great name BTW),

Thanks for this great advice - I will try all of this out over the weekend and report back on Monday.

ArtfulBodger - what do you mean "Disconnect the feed downstream of the valve"? There is a valve (a square headed screw in type a the 80 degree bend into the bottom of the cylinder, but I can't disconnect downstream of this as it bolts straight into the HWC.

One additional point that I need to get cleared up - I turned off the cold water feed to the cistern, the feed into the cylinder, and even the stopcock to the entire flat when I extended a hot water pipe (fed by HWC) in my kitchen. A trickle of water continued to flow through this pipe as if under some small pressure - can either of you guys explain this? Does this give a clue to the cause of my spluttering taps?

I really hope I don't find a rat, or a bird, or spiders, or....euggh

Thanks sincerely and have great weekends!

 

[mrcrow]

the ball cock might be sticking or partially blocked by a collapsed washer, in an intermittent way so that the flow may be drawing air from a low tank level..