Boiler running out of water

Staticpulsejen

Sure this has been discussed before, I have a 2014 installed 250 litre megaflo hot water immersion system boiler. I am on enconomy 7 electricity.
The boiler does not seem to be able to heat enough water for one short shower and a bath and one basin of dishwater. Even sometimes not enough for 2 short showers if there has been 2 basins of hot water used.
We have to take it in turns to wash as the water is regularly cold come the evening and don't want to use immersion switch. There are 3 people living at the house.
It is a rented property so I want to know if this is just normal for this size of tank or should I report to landlord and get an engineer in?

mmmmikey

Hi - minor point, but what you've got is called a hot water cylinder rather than a boiler. You certainly should be able to get a few decent showers from a cylinder that size, so either the immersion heater isn't set to come on for long enough or there's a fault somewhere.



Do you manually switch something on or off or just leave it running and let it sort itself out - don't worry about why I'm asking this but if you answer can point you in the right direction...

ianto11

Hi,
Few questions

• Is the cylinder only heated by electric, or do you have gas also ?
• Is there only one immersion heater on it ?
• Can you check the temp setting on the immersion, maybe it's been turned down ?

Shower and a bath would potentially use a substantial amount, especially if you like to "dwell" in the shower, and also depends what time of day your using water

Staticpulsejen

Thanks for getting back to me.
I just leave the boiler on and let it come on overnight on its own it's wired into my low rate meter to run for up to 8 hours on cheap electric overnight.
I live in an area with no mains gas so electric only.
I've checked and can't see any way of turning temp up or down.
In the morning the first water to come out is scalding hot. It does stay hot til the end of the day if nobody has used it.
My lodgers say they only have short showers. I think this is true as I can hear the water running and it isn't that long.
The specs for the boiler say there are 2 X 3kw
I wondered if maybe one has broken as when I checked this morning the bottom of the tank certainly felt colder than the top.

mmmmikey

Hi again

If it's all set up and working correctly, what should happen is:

1. Bottom immersion heater runs for every night on economy 7 night rate tarriff
2. Top immersion heater is not normally used and is just there to provide a boost later in the day if needed - it should be connected to a boost switch that looks something like this:
https://www.amazon.co.uk/Timeguard-TGBT4-Electronic-Boost-Timer/dp/B006SYK8U4/ref=sr_1_1?keywords=immersion+heater+boost&qid=1554799249&s=gateway&sr=8-1
the idea that you press it only if needed

So if the system is properly sized and working you shouldn't need to do anything.

When you use hot water it comes out of the top of the cylinder and cold goes in the bottom, so it would be normal for the top to be hot and the bottom to be cold towards the end of the day. But if it's like this in the morning before you've used a significant amount of hot water then something's wrong and you should get your landloard to get it checked out.

What sometimes happens is the bottom immersion heater fails (which normally happens first because it's the one that gets used all the time), the wiring is temporarily changed so the cheap night rate electricity goes to the top heater. This keeps you going but means that you don't get a full cylinder of hot water. The problem is that the temptation is to leave it like this. This is only one possible explanation, but would be consistent with the problem you're having.

One way or the other, you're not doing anything wrong and it should be working properly so it's fair game to call your landlord and ask to get it checked.

HTH Mike

ianto11

Hi,

As mmmikey says, sounds like the bottom immersion isn't working. You could check if the thermal cut out is tripped.
If you isolate the power and remove the bottom grey cover, you'll have one of these under,

http://www.heatrodshop.com/technical-faqs

this adjusts the temp (4 is normal ) Q4 on the page above tells you how to reset the thermal cutout....listen for small click when you push it in
If it resets, monitor the temp, if it trips again then the Cotherm stat needs replacing