No hot water in the evening

I have just moved to a flat with a Pulsacoil III and we simply don't have hot water in the evening. Sometimes it's warm but, after 5 minutes, it starts to get colder and colder until it's completely cold. In the morning, it works fine.

When we moved to the flat, the level of the top tank was low. We filled the tank and it started working - but not in the evenings.

(Apparently) there is no timer that regulates it. Any clue on what's the problem and how could we fix it?

Thanks!

Guessing you may be on an economy 7 tariff, so all water is used during the day and it won't re heat until the evening, normally midnight to 7am

Look at your bill and check, if economy 7 speak to Scottish power they have an economy 10 tariff, 5 hours in evening 5 in the afternoon, they sometimes deny they do this, but argue and they will find it,
alternatively fit a time clock, so you can control heat up times,

Economy 7 supply issue
Spur faulty
Bottom element thermostat faulty
Bottom element faulty

I would recommend you have an engineer out who knows the system and knows mains electrics. It is a nightmare when you have to start calling two separate engineers out and they keep bouncing you back and forth.

Best of luck

No sunny there is nothing wrong with that Pulsacoil, gselectrical is write, , he is on an eco7 tariff, call your electric company and ask for eco 10, this will sort you out,mate, no need for an engineer.
regards Master Mario at Mario's Boiler Service

Mario I have to disagree with you!.

No one has established if the system is operating correctly. The eco 7 timer calibration may be incorrect but still giving a 7 hour supply at a different time in the day. The thermostat could be faulty and cuts at a low temp. I am not saying the eco 7 is fine I have clearly said that could be 1 of many problems. I would recommend "get the electricity supplier in first to check their side".

carol136 wrote:I have just moved to a flat with a Pulsacoil III and we simply don't have hot water in the evening. Sometimes it's warm but, after 5 minutes, it starts to get colder and colder until it's completely cold. In the morning, it works fine.

When we moved to the flat, the level of the top tank was low. We filled the tank and it started working - but not in the evenings.

(Apparently) there is no timer that regulates it. Any clue on what's the problem and how could we fix it?

Thanks!

OK, let's go for the facts:
From carol's question, in the morning the hot water is fine. So no sensor problem or pump ,the eco7 has regardless if coming on long enough, heated the Pulsacoil up( this needed about 5 h to do so) for at least a bath /shower. As we know, from even the biggest Pulsacoil with 225 Litre capacity and a max flow of average 15 litre per minute ( 12 at a shower or 18 at a Bath tap),you will get about 200 litres maximum of hot water ( from a 225)or about mixed with cold 15 minutes run on the tap ( shower or bath). Considering the fact , the 225 Pulsacoil was hardly ever installed in small ( less than 3 bedrooms) Apartments, this is what you get and most likely use in the morning. Most Pulsacoil in Apartments are between 155 and 185, means also less than 200 ( 140 to 160) litres hot water to use before you run out. As there is no timer , means the signal comes direct from the off peak consumer unit / meter. So you can't time the bottom immersion yourself. Also the boost is not used ,otherwise you would state this in the question. ( hope I am correct so fare)
Resume, PCB ( or pump speed control board) is working , no sensor problems , no pump problems , no immersion problems, no thermostats problems. Watt's left is obvious and also I would not pay £100 to the electricity company to get told there is no problem with the off peak supply ( on the instated eco 7 tariff) . If carol also like to spend money for someone, to check the Pulsacoil , that's ok, but will not help with the problem. Changing from eco 7 to eco 10, will not cost any, except some phone calls and will heat the Pulsacoil 2x also at daytime ,at least partly to get water for a quick shower and washing up ect. in the evening.
Sorry,I just talking from my experience, as I have repaired over 12 000 Gledhill ( 5 000 Pulsacoil of all models at least)products over the last 13 years and was over a decade working as senior engineer for Gledhill ( the Blackpool based company HQ). By the way, I am now over 30 years in the trade as fully qualified master plumber and master heating engineer with C & G, btec ND and HND diploma.
Kind regards Master Mario at Mario's Boiler Service

Ok Mario, let me go into this in more detail. I have never indicated the sensor or pump are faulty. I have in all comment metioned eco 7 supply first.

I would recommend you call your electricity supplier and confirm you have an economy 7 or economy 10 supply. If they say you only have an eco 7, request them to come out and change it. If they say no just a 2 rate meter, check in the airing cupboard for anything that looks like a timer (You have said you can't see anything like that in there). What I would then check is if you have a timer or a control system such as a Nobo system in the same cupboard as your consumer unit (sometimes these are located there).

If they come and change the off-peak meter or calibrate it and the system is still not working correctly, I would then recommend you get a professional out who can check the mains supply and the unit.

A case last week similar to this was found to be the switched fused spur burning, so it was sometimes giving a supply and other times not.

Also just mentioning this, we went to a job where the thermostat rod was incorrectly set at 50oC and should have been at 75oC, this was causing insufficient hot water in the cylinder which was only giving them enough hot water during the morning and becoming colder and colder towards the evening. Mario I am sure you have seen jobs where the thermostat rod had been turned down or even replaced for the incorrect rod.

Please note that the unit is at its hottest during the morning and will start to cool down after, depending on how much hot water you use. You may be using more than the unit can store and may need to use the boost button or just get the eco 10.

As we all know , this Forum is set up for ordinary Householder /Customer with no intensive plumbing/heating engineering background. So the last ,we won't is to confuse Customer with things that could be also going wrong or are also wrong from our guessing. In this case, the Householder needed a competent person to visit and diagnose the system anyway. Of course, only a handful information are never enough to diagnose any problem on any Gledhill boiler. Otherwise there would be no need for this forum, where we all spend some of our spare time to help. Yes sunny I also have come across some of your mentioned faults over the years, but this is quite on rear occasions, so this only confused customers. And as we all agreed , if this is not fixing your problem , call a Gledhill competent engineer at your local aria , to fix the problem, course from there on ,this would not be a DIY- job anymore. The last, we all wont ,is Householder messing around on the wiring harness or PCB's without knowing what to do. There are enough other people out there, doing this and charging money for it.
regards Master Mario

I agree