Air in power shower

[lavinpj1]

I have a power shower in the bathroom which is supplied cold water from a tank in the loft. The shower empties the tank faster than it is filled from the mains, thus meaning that air gets into the shower system when the tank becomes empty.

The remedy, for the past 5 years, has been to take the panel off the shower, remove a small plastic cover, allow the air to flush through and put it all back together again. Although a pain, it was manageable as it didn't happen too often.

I'm now renting out the house and this isn't an appropriate fix for the tenants. Neither is taking shorter showers, apparently!

Is there anything quick and cheap that can be done here?

 

[Madrab]

Only solution would really to increase the cistern's size. What size of supply pipe does it have?

Depends on the throughput of the pump, but for 1 bathroom you should really have a 50gal tank up there to remove any supply issues.

 

[lavinpj1]

It's a 50 gal tank at present. The flow rate in the whole house is terrible, even to the kitchen tap which runs directly off the 15mm supply.

I've changed the internal stop cock and kitchen tap, which hasn't made a difference so I can only assume it's the supply. Severn Trent seemed less than interested, though.

 

[Gasguru]

Stick a flow limiter on the shower head/hose but have you checked the float valve in the cistern is operating correctly? The washer often distorts or the nozzle blocks reducing the flowrate.

 

[Madrab]

Good idea from GG above. Will drop the delivery pressure tho.

As far as the legal supply requirements are concerned then you have it covered with a 50 gal tank. That's roughly 230L tho, what are they showering FFS, the whole family at once in a cold shower lol???
How large is the HW Cylinder, as you run approx 2:1 on hot water with a shower? That would normally run out 1st, not the CWSC??

I'd do a mains supply pressure test too if the tank is running dry. Is it a flat? Is the main supply pipe, as it enters the property (not just running to the tap), 15mm?

 

[lavinpj1]

It's not the fill for the tank - it doesn't flow any slower than the kitchen tap. The flow is just generally bad.

Is something like this an option? http://www.plastomatic.com/venting-valves.html

 

[lavinpj1]

Well as far as the legal supply requirements are concerned then you have it covered with a 50 gal tank. That's roughly 230L tho, what are they showering FFS, the whole family at once in a cold shower lol???
How large is the HW Cylinder, as you run approx 2:1 on hot water with a shower? That would normally run out 1st, not the CWSC??

I'd do a mains supply pressure test too if the tank is running dry. Is it a flat? Is the main supply pipe, as it enters the property (not just running to the tap), 15mm?

Thanks. I will do a pressure test today. I have a feeling the outside stop tap is the problem here in such that it's limiting the flow. It's a split supply with next door and they say pressure/flow is fine.

If it is the outside stop tap, that'll be a bit of a pain as it's circa 1m under ground.

 

[Madrab]

That should be for your supplier to sort out if it's outside the property boundary.

 

[Gasguru]

It's sounds as though the shower pumps just too powerful and the cold cisterns too small.

Another option's to fit a float switch in the cistern to cut out the pump once the level falls too low.

Running the pump with air will likely lead to pump damage.

I hope you have the cylinder cold feed above the shower cold feed so that in the event of the cistern running low there is no risk of scalding...especially since you will be renting out the property.

 

[lavinpj1]

That should be for your supplier to sort out if it's outside the property boundary.

Yeh, afraid not. There's a shared tap outside the property but the one I think is the issue is in the garden. I think it's the issue because when it's turned off it ****es water out.

I'll test static pressure later and let you know.

 

[lavinpj1]

Another option's to fit a float switch in the cistern to cut out the pump once the level falls too low.

Thanks, I'll look into that.

Another option's to fit a float switch in the cistern to cut out the pump once the level falls too low.

I believe that's the case, though I didn't install it. However, the shower has a thermostatic mixer so when the cold runs out, the hot is stopped.

 

[Madrab]

Going back to my first point though, who are they showering? An elephant in pretty cold water?
A normal 5 minute powered shower would typically use 70-90L of mixed water at approx 2:1 hot to cold depending on who you ask of course, but say that's average. With a HW cylinder (you didn't say size) @ say 900x450, approx 120L, and with a 230L cold water cistern, then it should easily eat up all the hot before the cold is emptied. I can't figure how the cold is being emptied 1st??

 

[lavinpj1]

The hot water cylinder also fills from the same tank, if that makes a difference.

When I had the issue, it was usually when I'd take a 10-15 minute shower and then the mrs would take a similar length one fairly soon after.

This didn't happen all too often as she works unusual shifts but there's 4 tenants, all of whom will be getting up at a similar time in the morning so I'm concerned it'll run out more frequently.

 

[Gasguru]

8 litres/min is adequate....you'll soon get used to it.

 

[Madrab]

OK, that'll be why, and with the CWSC not filling as quick as it should will just compound the issue.

Ok, back to the CW supply then IMO.

Limiting the shower one way or another is the other option but with 4 tenants then would that be acceptable, the shower not as effective as before or shutting off during their shower? Always an option tho.