Weather / air pressure affecting shower?

[derekjackson]

Hi,
we bought a house a few years ago that had a pressure-fed shower system in the bathroom. It was a bit temperemental, and during the winter months, sometimes refused to work. As we neared spring and it warmed up, it started behaving correctly again. We found one trick to sometimes get it to work was to place the head upside down in the bath - it'd then spurt out a few jets (as if there was air in the system) before getting going properly.

None of the pipework is external, and our plumber put it down to a dodgy valve in the shower unit.

We had a completely new bathroom fitted last summer with a new pressure-fed shower system. The flow was a little weak, so we decided to have a shower pump fitted next to our hot water tank.

Once again, when we reached winter, the shower started refusing to work - even with the pump. It was as if it didn't have enough pressure to get the pump initially going. Once the pump started, the flow was fine. The only solution that seemed to occasionally work was turning the shower all the way to cold to get the flow moving, although it didn't always work on the coldest days.

Once again, now warmer days are on their way, the pump starts up fine.

The pipes don't get cold enough to freeze, so that's not it. I can't find a leak anywhere. Our plumber has put it down to another dodgy shower valve, but it seems too much like coincidence (different brands, etc). I don't now want to invest in another new shower, only to have it fail to come on again next winter. But equally, I don't want to go through the cost of fitting an electric shower (and essentially binning a working pump) if it's definitely the valves that are at fault.

Any thoughts? My wife (who wanted an electric one from the start) is so sick of it all, I need to make the right call on this!!

Thanks,

Derek

 

[Simon F]

Hello Derek,:welcome:along.

are the hot and cold both pumped from stored water?
do the pipe runs drop and rise again, giving possibility of getting air locks?
what height is the cold water tank above the shower head?

 

[derekjackson]

Thanks!

Both the bathroom and the hot tank are on the first floor. The cold tank sits above the hot tank in the loft. The pipes run up from the hot tank, across the loft, then down into the bathroom. Does that answer the 'stored water' query?

All other water feeds in the bathroom come from underneath the floor and seem to work fine (although the cold basin tap isn't very strong).

 

[Simon F]

sounds like there is a likely possibility of air locks on the hot water pipe if it goes back up to the loft.
is the cold fed from the mains?
if so you also have issues with uneven pressures.

 

[derekjackson]

I assume it's mains fed. What other way would there be? How would I tell?

So if it's an air lock and/or uneven pressure, what would my options be? Sounds like a new pressure-fed shower would still have the same old problems. Would I still have problems if I took the pipework up from the bath taps instead of a separate route across the loft?

Or is electric my only solution? In which case, I'd need to find a way to get a cable all the way to the shower...

 

[mountainman]

As Simon says, it is not a good idea running the tank fed supplies back into and across the loft again after dropping down into the airing cupboard.
Is your pump a twin (four pipes) or a single (two pipes)?

I also suspect that you have a 'positive head' pump. In your circumstances I would have used a 'negative head' pump.

 

[derekjackson]

It's four pipes. Which is presume then means the cold comes down from the loft only to be pumped back up again.

 

[mountainman]

Correct.
If we assume that you pump is 'positive head' then there may not be enough water flow to activate either of the pump flow switches, hence you drop the shower head into the bath, increase the flow and the pump starts.

Negative head pump or maybe your existing pump has a conversion kit available. IMO
Whichever way you go I recommend an electrically competent plumber do it for you.

 

[marinegmillie]

hi, maybe the head of the cwcs is only just enough to opperate pump without the two feeds from pump been vertical going back into loft could cause that bit to much resistance stoping the pump from turning on, also maybe air playing a part.

 

[derekjackson]

I'm beginning to think that easiest thing would be to fit an electric. Take the (decent) cold feed from the bath tap below, removing all future issues with potential air locks and unbalanced feeds. It's throwing yet more money at it, but if it fixes it for good, it's prob the way to go. And I might be able to sell a second hand pump somewhere (only had it half a year!)

Does that sound like it would solve the air lock problem for good? I'm assuming they don't occur in mains pressure cold pipes?

 

[mountainman]

Electric not a patch on pumped thermostatic.

If your better half likes a good shower and you like big time brownie points, I'd recommend you splash the cash and change the pump.

Subject to getting a second opinion from an expert (I mean a site visit of course)

 

[marinegmillie]

repipe from pump along under floor to bathroom

 

[derekjackson]

Piping under the floor is out (recently laid new carpet in hallway, up and down a few steps, etc).

Getting a cable to the shower would be much easier.

We've also had issues with the pump draining our (relatively small) hot water tank.

My wife is sick of the whole thing and wanted electric in the first place, so I think that's the way to go.

Thanks everyone, for your help. Feels like we're finally getting it sorted.

 

[mountainman]

Wish you'd mentioned the issues with the small hw tank in your original post!

 

[derekjackson]

Ah - didn't realise it would make a difference!

Would that be where the air locks would be coming from then? (Bare in mind we had the issues before the pump arrived, and only in winter)