GEC Nightstor (no it shouldn`t have an "e" on the

[colport27]

Help.....
Ok enough drama, have any of you fellow "electrically knowleged people " had any experience with GEC Nightstor Heaters?
A friend of my wife`s has one and I have just been round to take a look as apparently it stopped working.
On first appearences one of the two thermal links has disintergrated (the one that has the daytime boost option). Now Im working along the idea that these things blow for a reason.
The tennant reported that there was a strong smell of burning plastic earlier in the week before all stopped working.
So far I have found the following..........both elements have the same reading with the fluke metre.
Pump is running fine, room thermostat working fine, i swapped the thermal links over just for a few minutes , so I could put the daytime boost on.....things started to heat up within the heater.
The overheat cut out at the bottom has not popped out.........so assuming that that is ok (would think the pump wouldn`t be running if this had cut out?).
The fan for the heat exchanger......did not run at anytime while I was there (impossible to get to any terminals on it safely while live).
Could it be possible that if the fan for the heat exchanger failed........too much heat would build up and melt the thermal cut out? My only theory so far, though I wouldnt want to suggest replacing it without further input from you guys.
Any assistance greatly appreciated........

 

[Steve]

someone posted a few weeks ago, about a thermal link melting (dont think it was a storage heater though). turned out they had left it on for a week, which weakened the thermal link sufficiently for it to melt.

 

[colport27]

I saw that post as well crafty, to be honest I didn`t realise these things existed...........fortunately they don`t seem to popular.
When I swapped the thermal link over to get the daytime boost to work, after only about 5 mins there was a slight plasticky smell.
Im still of the idea that it could be the fan, but as I said before would rather have a more expert opinion before trying that theory out.
For those that don`t know what one of these is......(only for future reference if someone else finds one).
Its basically a night storage heater (19.8 KW !!) stands about 6 feet tall about two foot square. The idea when working is the core heats on off peak rate, the fan in the bottom of the unit then draws the retained heat through a heat exchanger, then an integral pump pumps the water round the radiators.
Ok it`s slightly more complicated.......but thats the basic idea.
Unfortunately within the user manual and installers guides are only drawings of the control panel wiring, nothing relating to the terminal block withing the heater itself.
One of the guys at work used to install these while working for the board years ago, but again didnt have to fault find/repair them.

 

[crystal ball]

Someone on screwfix forum has been asking about the Nightstor, here is the reply
My God those bring back nightmares from my apprentice days from EMEB. (Lugging Bricks)

As for servicing them and installing them you used to have been registered by GEC and been on their course. No idea if this is still the case.

From memory (Last helped install them in 1987 but I have had to reset on in 1999) these boilers had two banks of elements both with thermal links which heated a brick core which "charged" during economy seven times. When heat is required air is drawn over these bricks and over a heat exchanger to heat the central heating water. The pump is internal to the casing. There is a reset button either behind the bottom panel of the boiler on the older models or behind a rubber plug on the later models (No need to remove the panel - Just push the middle of this rubber blank until it clicks)

The "Nightstore 100" were either configured for 3-phase or single phase (Supplied via a double supply cutout). Control was via a wall mounted control unit sited near the boiler. This contains contactors that either energised both element banks for 3-pahse or switched banks for single phase.

Basically failier wise you could of lost one or both elements, their themal links, the plenum chamber fan or the contactors.

As for service contractors try contacting the current manufacturer of this boiler at:-

http://www.hes.co.uk/compact-nightstore.html

Good Luck

--
JPW

 

[Lectrician]

Where does the pump come into play?? Not familiar with this heater.

 

[crystal ball]

Its like a central heating boiler but works like a storage heater, heats up bricks on off peak and uses a fan and heat exchanger to heat water which is circulated through rads by a pump

 

[colport27]

Thanks for the link Crystal, I emailed the guy this morning......Tony, seems quite a helpful chap.
Just awaiting a reply from the second email.
I must say though, I`m glad I have never had to install one of these things, thought it was bad enough carting a few bricks for a normal night store heater. The amount of bricks in these things and they way they have to be configured must have been an absolute nightmare.

 

[colport27]

BRAINWAVE !!!!!!!!!!!!!!!!!!!

Crystal........something within that post made me reread it a few times..
Even though we had an old installers guide, nothing mentioned the fact that if on a single phase supply it only operated one element at a time.
I assumed (wrongly) that both elements would operate together, now this may be stretching things a little but..what if...
The thermal link that had melted.........melted a long time ago.......not recently, the heater has been making use ever since that time, of the one remaining working element.
When my wifes friend mentioned the smell of burning plastic, I automatically went to the heater 1st and discovered the melted thermal link, therefore assuming fault with heater.
I never even looked within the control panel on the wall as when i swapped the links over, switched the daytime boost on.the element started to heat (therefore assumed control box was functional).
I now have a strong suspicion that the smell of burning plastic is possibly one of the contactors withing the control panel. As anyone here who has seen one before, a burnt out contactor reeks.
Will try and pop round and try this theory out tomorrow morning.
Thanks.

 

[colport27]

The plot thickens,

Well it`s still not fixed, and it wasn`t a contactor burnt out.
The unit is 3 phase, Red- control circuit, Yellow- element one (with melted thermal link), Blue- element two (with only 10 volts between phase and earth).
Appears that the 3 phase mcb at the mains position is up the shoot, 240 on all incoming, 240 on red & yellow load, 10v on Blue. Slight signs of discolouration to outgoing blue phase, possible loose terminal at some time causing it to overheat.
So what came 1st ? the chicken or the egg ?
Possible that the blue phase has been missing for years and the heaters been working on the one remaining element, until the thermal link blew............or...........thermal link has been blown for ages and now that the blue phase is shot........no heater.

 

[robgun]

I am changing my current GEC Nightstor 80 to a LPG boiler, can anyone tell me the 'modern' equivalent in kW i need to heat my house?? Also does anyone want it???
rob