We recently bought a new house and because we are in our 70's we cannot carry butane gas bottles on the flight of stairs to our kitchen so had an electric boiler which has been in for one month. We have also bought a Grohe Thermostatically Controlled Shower Bar for the shower but we are having problems keeping the water hot whilst in the shower, abougt 3 min is the maximum before it starts running cold, I barely have time to wash my conditioner off my hair and it is cold when I am doing it. Our plumber told us to turn up the boiler temperature so we did to 55c (the boiler is an 80L - supposedly sufficient for 2 good showers) but when you get in it is too hot at 55c and after a minute you get in and it is running cold after about 3 minutes which is most frustrating (I tried using it with the thermostat set at the standard 38c and it wasn't hot enough for me so we turned the valve up to 45c which made no difference to the length of time it stayed hot. After some research I have found out that the boiler can only supply approx. 6-8L of water a minute for a good shower, whilst the Grohe shower bar delivers 21L per minute and the shower head itself delivers 3 bar / 14L per minute.

Something is not quite right as some people have told me they have a good 10 min shower out of an 80L electric boiler but the boiler is only 2Kw power and I believe that we need a higher performance boiler to produce a couple of decently hot showers for more than 3 minutes.

Any plumbers out there that can advise us what to do ?

We have a standard type 80 ltr electric water heater. We also have a standard type shower operating from the boiler. I have the boiler on a timer so that it heats up overnight on low rate electric and also again late afternoon when it's mid rate electric. That is sufficient to provide hot water for showering and general use throughout the day, it is very rare that we need to heat the boiler in-between the times I have set on the timer. We certainly get our full showers out of that without any issues. What temperature our boiler is set at I don't know , I know it gives out very hot water on full hot but we adjust that from the shower or tap controls to suit what we need. Is your shower on a pressure pump ? Ours is simply mains pressure which provides a more than adequate shower pressure. Clearly something isn't working with your set up if it's using 80 LTRs of hot water within a few minutes.

Our boiler doesn't even have a programmer on it. The plumber we asked to put in the boiler didn't seem to think we needed it 🙄 It is mains fed with no pump attached to it. He said to keep it on 45c and it would be plenty hot enough. When we complained of the shower not being hot enough, he came and took off the end of the shower bar and moved the thermostatic valve so it would get to 45c and then turned on the water on the shower and asked me if it was hot enough. I put my hand in it and it was luke warm and I said "No Way" ! I like my showers hot and he just suggested turning up the thermostat on the boiler to about 55c. We did that and when we went to use it the next time we waited for the hot water to come through, about half a minute and it was boiling hot so of course I couldn't get in it, waited about 1/2 a minute for it to cool down enough, got in and as I was it lasted about 3 minutes, I had just put the hair conditioner on my hair and mixed it in, came to wash it off and the water was stone cold ! If our shower head is pulling through a shower flow rate of 14L from the boiler, surely it is not going to stay hot for long is it ? By the way is your electric boiler in your bathroom? Ours is on the floor above and I wonder if that makes a difference with how far it has to travel to the shower head 🙄

I wonder if the issue is that the water pressure is to low and the plumber may also be an issue.
BTW Grohe is a good brand in my experience

Our boiler isn't in the bathroom it's in our bedroom which is on the same level as the bathroom. Our shower is just a standard shower head from a basic shower mixer tap to adjust temperature mixing cold with hot. It works fine and gives a good shower. Our shower tap isn't thermostatic so that may be the difference.

Grohe is a good brand that we also had in the UK but that operated from a Combi boiler which obviously keeps the temperature constant. I don't rate the plumber as he doesn't seem to understand how flow rates affect the performance so I did look it up online about the flow rate . So presumably from what it says a 14Lt shower head rate from a boiler which can only handle between 6-8L a minute is going to cause the temperature to drop dramatically in a short space of time because it can't heat the water coming into the boiler quickly enough for the rate it is flowing out! Looks like I might need a shower head with a lower flow rate !🙄

You are describing an "instant" water heater, but you say you have an 80-litre water tank with an immersion heater. I have used these for years with a high-pressure pump and never had a problem. I suspect the thermostatic shower control. Try changing it for a basic shower mixer tap.

It is an electric boiler, not an immersion heater, it holds 80L of water, we bought it here in Spain, it does not have a pump. It's not "instant" if it takes it about 40 mins from cold to heat a tank of water. Our problem is as soon as you get in the shower and turn it on, it has a long way to come from the boiler and takes a minute or two to get hot and then it only lasts about 3 minutes but then as I say, if the shower head is delivering 14L of water a minute and the boiler holds 80L and the cold water is running into the boiler within half a minute or so, it only takes about 4 minutes from when you turn it on to empty the boiler of hot water and it is running almost cold. I think it must be the shower head but I am open to advice from a professional.

From what you describe it sounds more or less the same set up that I have although I do not have a thermostatic shower control. It is in fact really just an 80 ltr capacity immersion heater . Ours takes a little while to get hot water first thing as the length of run from the bedroom to bathroom. As Fred says I would suspect the issue may be the thermostatic shower control. obviously you only have 80 LTRs of hot water but when you mix that with cold via the standard shower control tap you get more than 80 LTRs of water to shower with. You want the water in the heater to be hotter than temperature you shower with and using standard mixer get it to the right temperature mixing with separate cold water input, thereby extending amount of water at suitable temperature to shower. Like Fred that's the system we have used for last 18 years without issue. Only issue we had when we first bought the house was that the water was from the mains fed deposito and pressure was near zero in bathroom so I added a bit of pipework so that we get near mains pressure to feed the shower taps etc in the house and also fill deposito for emergency use for any mains cut offs. Is your water boiler on all the time heating the water ? Mine doesn't have an internal timer but I fitted a simple timer to it which works well.

Yes it is on all the time. I would like to fit a timer to it it though if we could. I asked the plumber when he put it in if it had a timer programmer on it and he said no, you don't need one, just keep it on 45c all the time and it should be OK. 🙄

IThat sounds quite a low setting but I am no expert . My temp control isn't in specific temperature I just have it on quite high and that allows us to mix it with cold via shower and tap mixers .

Yes there are so many different variations in both electric boilers and showers, it is difficult to know what goes with what these days and I am a technophobe when it comes to the intracacies of putting these components together that match !🙄

Of course it’s an immersion heater, how else do you think it heats up. It’s a tank of water with a heating element in it. That’s an immersion heater. It’s a heater immersed in water hence the name. Just change the shower thermostatic mixer and see if that fixes it. And find a decent plumber!

I believe Spanish electric boilers have TWO tanks with an isolated heating element 😉 We don't have a mixer shower bar, we have a thermostatically controlled bar which cost us 160 euros just a month ago 🙄 If we can find a cheaper alternative to changing that, then that will suit us !

Of course it's a mixer tap, as it is connected to both hot and cold water supplies. The thermostat in the mixer controls the amount of hot and cold water. Just Google it if you can't understand such a simple bit of technology, or, as I said earlier, find a decent plumber.