Really need some help....

treecol

We used to have an electric shower before we moved, fed as yours is straight from the cold water. The flow reduces as you turn the heat up as it can only heat a certain flow. As a previous poster said, with a combi boiler you'd be better with a direct feed shower with a mixer - then you'd get a good strong flow. We had that 2 houses ago with our combi. It would blast the water through.

matelodave

Electric showers heat cold water directly from the mains. Therefore as the incoming mains water gets colder (winter is coming) they usually reduce the flow to try to maintain the temperature.
This means that they don't perform as well in the winter as in the summer - they also cost about 3-4 times more to run than a shower fed from a gas boiler (unless you've got E7 and shower between midnight and 7am)

Pincher

missy81981 wrote: »

What does that mean?

Ask Google. I normally use Windows and Internet Explorer,
and the Android tablet managed to mess up even my signature, this time.


Any way, scalding prevention means that if your incoming water is too hot, i.e. already heated by a combi, the shower will reduce or cut off the flow. It's designed to heat up cold water, feeding it hot water is confusing.


Touch the incoming feed, if it's hot, then that's your problem

matelodave

I'd doubt that any plumber would connect the inlet of an electric shower to the hot side of the combi unless he was totally incompetent.

Pincher

The worst plumbing horror I have seen is a naked guillotine switch, close to the shower head, with two wires going into the shower head, which has a heating element to heat up the water.


The element would burnt out if no water is running to cool it down, so you must run the cold water first, then pull the guillotine switch.


Subsequently, I saw the shower head in department stores, and it was the standard solution for the "modern" apartment, where the shower is located in the toilet cubicle, in 1990. You stand on the Turkish style squat toilet, which you still see in Paris quite often, so your shower flushes the toilet as well.


Unlike a billion Chinese people, I was not brave enough to have a shower that day.


DIY, cowboy, mad scientist, who knows. The guy who walks into B&Q could be a fully qualified heating engineer, or the next Unabomber. Actually, I find the professional usually use Plumbcenter, probably because they let you have an account, and you can enter a job reference per order which is handy for paper work.

brewerdave

No way of knowing where the pressure reducer/filters will sit on your system - you need a "competent" person to look at the water feed to the shower -should be "unique" -but might be teed off the cold feed to the bathroom sink/toilet flush??

lstar337

Pincher wrote: »

Ask Google. I normally use Windows and Internet Explorer,
and the Android tablet managed to mess up even my signature, this time.

It's MSE Pincher, they are combating a huge SPAM overload and lots of posts are getting garbled. I thought it would be gone by now.

http://forums.moneysavingexpert.com/showpost.php?p=66727034&postcount=1

snowscreamer

CashStrapped wrote: »

The best set-up for a shower on a combi boiler is a shower directly fed from the combi with a mixer tap (with thermostatic valve).

You have actually taken a backwards step in my opinion.

An electric shower is always limited by their size in KWs. They can only heat so much water by so many degrees at a certain flow rate. The hotter the water needs to be, the slower the flow.

It is like having another mini combi boiler in your bathroom, but it just runs on electric and is no where near as powerful [as your actual combi] and more expensive to run.


Regarding your issue though:

Are you in a hard water area? Is there a filter on the feed pipe for the shower? there could be some debris suck which has reduced the flow.

I agree totally with this. In my previous flat I did the opposite: a year after I moved in I removed the Triton electric shower that the previous owners had left and replaced it with a Triton mixer shower (ie. normal shower fed from cold and hot feeds - hot water from combi boiler).
For a constant output temperature from the electric shower (mine was 9.5kW) which is fed only from cold water feed, the colder the input feed, the slower the output. We measured the flow rate in March and it was 4l/min. It varied noticeably as the seasons changed, I reckon it was 3l/min at the coldest in the water, 5l/min at the warmest in the summer.

So I changed to a mixer shower, this is fed from both hot and cold feeds and adjusts automatically how much from each feed to reach desired temperature therefore flow rate doesn't very. I was getting 10l/min from this: much improved!! Running costs were also slightly lower as although the flow rate was much higher and therefore more water was heated, due to the fact gas was used rather than electricity it did work out a bit cheaper.

As far as I am aware, there are only two advantages to an electric shower,
1) you can still have a hot shower (albeit a measly flow rate!) if your boiler breaks down
2) as the hot feed isn't used (this applies to combi boilers only), you can use other taps in the house for hot water at the same time as showering without flow being affected on either side. So after I had the mixer shower fitted at my old flat, you couldn't use hot water elsewhere in the flat whilst someone was having a shower. A small price to pay for a decent shower IMO.

In my current house, the set up is an AquaLisa power shower (ie. pump assisted mixer shower) fed from hot and cold feeds. And I have a system boiler with hot water tank, so don't have the problem where you can only use the hot water in one location at a time. It gives a pretty good flow rate too, although I haven't measured it.

Pincher

Don't forget there are HIGH pressure and LOW pressure mixers.
If you are going to rip out the Aqualisa, and put in a thermostatic mixer.

Best to get a pressure figure, to help planning.
My plumber tried to fudge it by using a measuring cup, which measures FLOW, not pressure: because he can't be bothered to find his pressure gauge. It's best to have BOTH FLOW and PRESSURE.

CashStrapped

snowscreamer wrote: »

IWe measured the flow rate in March and it was 4l/min. It varied noticeably as the seasons changed, I reckon it was 3l/min at the coldest in the water, 5l/min at the warmest in the summer.

Apart from debris in the shower head or water inlet filter, this

could be the very reason for your pressure loss.

The ambiant temperature has dropped in the last few weeks. Therefore the temperature of the cold water supply (which an electric shower uses) may indeed be much colder that it was a few weeks ago. This means your electric shower has to work much harder to heat it up. Therefore as I said in my initial post, the flow will be reduced.

So, it could just be because of how cold the water is at this time of year. Everything that needs to heat cold water at this time of year will have to work a bit harder. Kettles will take a bit longer to boil cold water, and gas boilers will work hard to heat up water.

However, because an electric shower is not that powerful compared to a combi boiler, it has to reduce the flow a lot more for a given temperature.