Data logging

[SidOnYerFace]

Hullo

Landlord here. Yes, I know, probably you all hate me, since I'm responsible for the entire credit crunch.

However, I have a technical problem and am seeking help. Please.

I have an apartment with a Gledhill Pulsacoil 2000. Don't weep for me - just throw money.

It's had some work done on it recently - new immersion element, two new immersion stats, new pump, new heat exchanger, and I've since had a good lie down and recovered from the bill. Now the problem is that the water just isn't getting up to heat in the standard configuration.

As an experiment, the engineer has left it in such a way that the lower immersion element is available to be used 24 hours a day, instead of just during the off-peak period(s). This is great. Happy tenant == happy landlord, in theory. But this isn't as per the Gledhill design. The primary water is supposed to heat up, and thereby store heat energy, overnight, and release energy (via the heat exchanger) the rest of the time.

If the wiring is changed back again then the tenant can have a hot shower for a couple of minutes, then he says that the water goes tepid.

So what's the question? Well, I want to [somehow] record the pattern of electricity consumption in the two configurations, so that I can compare them. (Current in x time) == energy available, and I want to be able to see what's happening overnight without standing there for 7 hours with a clamp meter and a stopwatch.

There seem to be expensive (to hire or to buy) data logging devices that will do this, but I think my needs are less sophisticated then the price tag of these thingies imply.

Do any of you have an innovative way of solving my problem at low cost? And by "low", I mean that I'd be happy to spend around £25 on some device to do the job.

Thanks.

 

[plugwash]

I can think of possible ways to do it (something involving an optoisolator and a pic most likely, remember you only have to monitor on and off since the thermostats in heaters juse use on-off control) but unless you have previous electronics experiance it would be both challenging and potentially dangerous (mains and electronics are a combination that requires extreme care)

 

[flameport]

As an experiment, the engineer has left it in such a way that the lower immersion element is available to be used 24 hours a day, instead of just during the off-peak period(s).

What exactly have they done to acheive this?

As the elements clearly work, the problem is power not getting to them at all, or for long enough.

The lower element is switched via an external timer or other switch, probably next to or part of the electricity meter. What have you got - a timer / teleswitch or some other devices?

The other answer is that the isolating terminals on the control board are not installed or are loose, so no power gets to the element. (these are located to the left side of the control board at the top of the cabinet, so they can get as hot as possible )

 

[SidOnYerFace]

Thank you plugwash and flameport.

In answer to the question "What exactly have they done to acheive this?", it was done by connecting the feed to the lower element to the DP switch supplying that was supplying the upper element, and leaving the upper element disconnected. The appliance has a handy connector strip whereby this was safely achieved in about 60 seconds.

I agree that the problem is power not getting to the element for long enough. The factors affecting this are:-

a) The timer switch wotsit thingy.
b) The element thermostat.

For example, if the thermostat was switching off too early, such that during an 8-hour period it wasn't on for long enough, but during a 24-hour period it was, then it would account for the symptoms.

This is exactly why I want a data logger. The 'time on' duration would be simple to calculate if there weren't any other appliances on the off-peak supply, but unfortunately there are night storage heaters.

I don't have enough electronics experience to construct anything with an optoisolator and a pic, so I suppose I'm looking for something proprietary, but cost-effective.

 

[TicklyT]

How about an old-fashioned mains powered analogue clock?

Set it to 12.00, connect it up to the off-peak supply, then see what time it reads the next day. Then you know how long the off-peak supply was on for.

Same clock connected across the control off-peak output would show how long that is switched on for

And connected across the immersion element terminals, it would show how long the immersion was switched on for, in case the thermostat isn't behaving.

You could use a plug-in mechanical timeswitch in the same way.

 

[toasty]

I recently bought a multimeter from maplin that could do what you want, you could either log the voltage at the element or break the circuit and measure the current.

http://www.maplin.co.uk/module.aspx?TabID=1&criteria=usb&ModuleNo=46381&C=SO&U=Strat15

It's forty quid though, might come in useful again...?
You'd need a laptop too, to log the data - but I can confirm that it does work pretty well.


As an aside, I bought mine to log the effect of that 'earth day' thing, where everyone was planning on switching off their lights for an hour.. I figured that this would probably result in a noticable increase in both grid frequency and voltage, so set one of these up to log it all. They work very well.

 

[LiamPope]

As an aside, I bought mine to log the effect of that 'earth day' thing, where everyone was planning on switching off their lights for an hour.. I figured that this would probably result in a noticable increase in both grid frequency and voltage, so set one of these up to log it all. They work very well.

Out of interest - did you log anything interesting? Would be interesting to know how much such a sudden and significant drop in demand (assuming this venture was successful) could have varied the frequency before the power plants' control systems pulled it back in line. >1Hz and colour me surprised.