Is this the only way....?

[Orion917]

I need help and advice with my house water system. I have a three storey house, your standard 1930's bay fronted semi-detached with a loft conversion. We have a bathroom with showers on the middle and top floors and an additional toilet on the ground floor. We have gas CH served by an Alpha CD20S system boiler coupled to a 200l MegaFLow tank on the middle floor. We now basically have four adults living in the house (my kids have grown up!), and it has reached the stage where we need to make an appointment to have an uninterrupted shower! We can run one shower very well, both are mixer showers, but as soon as anyone else runs a tap or flushes a toilet you know the result. Much dancing in the shower! Pressure at the outside tap near the stop cock measures 2.7bar static and and 1.6 dynamic (whenever I have measured it), and flow can be measured in the top shower at 10 l/m when it's running well. However, it can be practically zero when it's not or anywhere in between causing temporpary disruptions. When we had the loft converted (circa 2008) I asked the plumber to fit the best solution that would provide a good shower in the loft, hence the system boiler and Megaflow according to him, but the problem appears to be lack of cold water pressure or flow or both.

I've looked into this a bit and your standard Salamandar pressure booster doesn't look like it's going to help me. I found the Powertank water boosting system on line so I rang the company and they say it will be ideal (they would of course). It's not cheap by any stretch but I am prepared to pay the cost if it sorts out our problem. We would like to at least run one shower without fear of it being interrupted by running taps or flushing toilets. That would be fantastic.

Can you let me know what you think? Would a pressure booster set be the solution? If not any advice welcome.

Cheers.

 

[just pumps]

DAB do a pump but dang if I can remember the name right now

 

[Madrab]

Looking at those figures then dynamic pressure may be your downfall unfortunately, that being said it would be interesting to understand what is the max flow you can achieve at the highest point with nothing else on, ideally a free flowing basin tap or similar. If you're getting approx 1.5 bar dynamic (how many outlets open at the same time?) then that may be your issue. To have a true dynamic figure though as to how it affects your needs then you need to have as many outlets open at the same time as you would have if all the showers were running (remember that's hot and cold supplies running at the same time). You also have to add the height from the test point, as that will manifest as a drop at a given outlet so if you take the readings at ground level and the water has to travel 5m to the attic then that almost 0.5 bar lost as well.

These are all factors that need to be considered.

You also need to know the max that can be delivered by the mains, that would determine whether an upgrade to the mains would be the solution or not.

Out with all of that then you need to understand the max draw you will have on your supply, that may be 1 shower running at the same time and if the washing machine or kitchen is to be used at the same time.

 

[Orion917]

OK thanks, indeed, lots to consider.

I ran both showers this afternoon at the same time. Both continued albeit with reduced flow. I checked the dynamic pressure again and it showed 1.0 bar.

 

[Madrab]

That's certainly part of the problem then, are you rural or suburbs/city? Your sustained pressure isn't up to driving more than one decent without impacting on the others. That should have been surveyed by your plumber TBH and they should have known this could have been an issue. I take it your unvented was commissioned properly and benchmarked (signed off)?

I'd be inquiring with the supplier what the mains flow and pressure is, probably find it's pretty good and it's your supply pipe that's at issue - mains from the street to your property.

You could look at an accumulator but it kinda defeats the purpose given you already have an unvented. Usually they wouldn't go together as the unvented shouldn't have gone in unless the mains could sustain it. The other option, if the mains is good, would be to replace the supply pipe.

 

[Orion917]

I'm in a city. The water pressure is variable. My Mum lives across town and her mains water blasts out. Water pressure where I live is not as good, confirmed by other neighbours. The install was done circa 2008, I got all the blurb install docs for the boiler and the megaflow, other than that I don't know what else he did to check it would work. It was and still is not my area of expertise. I'm an electronics engineer!

Searching the threads on this forum, I've seen a lot of reference to upgrading the mains supply pipe. This will be challenging, theres 5m across the patio to the side of the house, 10m up the passageway and 3m to the street stop cock. All under hard surface. This doesn't sound like a viable cost effective solution to me, hence the thought of the booster pump.

 

[Madrab]

This doesn't sound like a viable cost effective solution to me, hence the thought of the booster pump.

Fair enough, sometimes a mains upgrade isn't always a viable approach but in a lot of cases it can be the most cost effective approach in the long run, If it's a step too far for you then what are the alternatives.

I don't think a mains pump would give you much more than you have at the moment as they top out at 12L/Min @ around 1.5bar and if your mains will deliver that already then it won't run most of the time. A pumped break tank (powertank) may also be a bit over the top as it is expensive, as you mention, noisy and takes a lot of space to set up properly and to give the capacity you may need, it may be a substantial installation

An accumulator may be your best option - depending on the size it will top out at the highest pressure that the mains can deliver throughout the day/night but that will only last as long as the size of the accumulator and then it would revert to the normal mains pressure, usually these are installed oversized. Again though it comes down to a very accurate usage survey and an experienced installer who knows what they are talking about.

You can get pumped versions of these but then you're back to excessive cost and space.

 

[Orion917]

Yes, great. Thanks for your insight. Not an easy one for sure.