Replacement cold water tank

[Grenage]

Our power shower starts making a whine and then the water goes cold after an average shower duration.

Average for me, not the missus.

I legged it upstairs after the last time, and although the water wasn't at the outlet level, it was within a couple of cm. It must be the tank size, because if you wait a few minutes you can get a bit longer out of it.

So are there any special considerations when sizing up?

While I'm on the subject, after the inlet valve was changed about a year and a half ago, I've noticed the sound of running water whenever the tank is refilling. If I'm in the downstairs toilet I can hear a 'wooshing' sound. Could the new valve be too restrictive on flow?

 

[KenGMac]

Grenage, good evening

Any chance of finding out what size the tank is?

Ken

 

[Newboy]

and although the water wasn't at the outlet level, it was within a couple of cm

There will (probably) be at least two outlets - one to the cold water supply & one feeding the HW cylinder. From your description, it sounds like the level has dropped to the point where there is no feed to the HW cylinder.

(This assumes that you have a HW cylinder!)

 

[Grenage]

I can only see one, so I that will be the hot water tank; everything else appears to be mains.

 

[KenGMac]

The tank sounds like a "Header Tank" rather than a "cold water storage tank?"

If one shower is running a tank dry the tank must be quite small???

Ken

 

[Grenage]

Ah that's the right term? It's not that large, but I'm not sure how high it fills. I'll check that out tomorrow, I'll also figure the capacity.

 

[Newboy]

Assuming that you have one, what type of hot water cylinder do you have?

 

[Madrab]

What are the cold water cistern dimensions?

The longer it continues, the more potential for damaging the pump will be. Running any pump dry is not a good idea

 

[Grenage]

Hi guys,

The tank is approximately 70w x 53d x 50h (cm) there's a good 10cm from the resting water level to the overflow, so I can gain a bit extra there.

I was mistaken in one outlet, there are two. I believe the second outlet must feed the cold to the shower, so effectively both the hot and cold are being fed through the header tank.

Edit: Is it acceptable to add a second cold water tank and link them together? I assume it would need to be connected low-down so as to reduce water stagnation.

Alternatively, I'm pretty sure this was fitted when I replaced the valve. Can swap the 'cone' for a lower pressure piece, or will that compromise the overflow?

 

[Grenage]

Shameless one-time bump.

 

[Newboy]

It's quite easy to fit a second tank but the inlets and outlets need to be arranged carefully to ensure that portions of the cistern don't stagnate.

Better, in my view, to fit a larger cistern - if access via a loft hatch is limited then a coffin tank is the usual solution.

 

[Grenage]

Cheers. My only concern with a larger tank is the additional weight - the existing tank isn't over a wall. Access is easy as half the loft was converted, so there are standard doors for admittance.

 

[KenGMac]

Shameless one-time bump.

No shame.

OK, if you replace a high pressure ball valve inlet for a low pressure one then there is a good chance of trouble, along the lines of double the inlet dimension and an increase of pressure will follow?

As for a "Twinned Double tank" yes that should work you are in fact doubling the available volume of water which in turn means that it will take much much longer to empty

In fact if you opt to fit a rectangular tank of [if you can find one

 

[Grenage]

Cheers, KenGMac; that makes sense.

I think I'll get a second 50gal tank and link them at the base with a run of 22m copper. I can spread the weight more easily, and I'll only have to move the inlet pipe, so less faffing with the overflow and two outlets. The tank should be ok on another bunch of joists, after all, the existing one hasn't gone anywhere. Good opportunity to replace that quarter-turn isolator on the inlet, too.

I'm not sure if I should have a ball valve inlet in each tank yet. I'd better do some reading.

 

[KenGMac]

Grenage, good morning.

Can I suggest you consider one inlet, that will fill the two tanks, a connection between the tanks [as you describe] and put a stop valve on that connecting pipe, that way if needed you can "isolate" the second tank.

As you say the twin tank stops a load of re-plumbing and work? and the above cuts work down a lot as well?

Ken.