Help me find a dual rate electricity meter please

[ProDave]

I am needing a dual rate electricity meter for my own use.

This is for my new build house. I want to monitor the electricity consumption of my Air Source Heat Pump and want to monitor how much it is using for heating, and separately how much is us using for hot water.

So I thought I can use an ordinary dual rate electricity meter.  I have a 240V switched output that is only on when it's heating hot water so can use that (with a relay if needed ) to change rate on the meter.

So I started looking on ebay for cheap dual rate electricity meters.  This is the only one I have found so far https://www.ebay.co.uk/itm/Electricity-Meter-Landis-Gyr-Single-Phase-2-Rate-Meter-100A-OFGEM/202431887856?epid=1627086932&hash=item2f21e179f0:g:7iQAAOSw0F9blVX0

But that is no good, that one has an inbuilt radio teleswitch so the rate switching is done at fixed times.  I need the old school type where the rate switching is done by an external input.

Any ideas where I might get one?

 

[Andy™]

isswww.co.uk sell meters. not sure which would be suitable for your use though but you could ask them

 

[Tony S]

Why not use two bog standard meters?

 

[Blue Duck]

Din rail meter work? 

https://isswww.co.uk/dds353-45a-direct-connect-single-phase-kwh-meter?

 

[Sharpend]

I suspect Dave wants it/ them located in an easily accessible position that’s not too intrusive. 

 

[Tony S]

If the required readout is remote the revenue meter then CT’s may be needed to save on wiring CSA.

 

[binky]

not sure a dual rate meter will do what you want, lots of meters have terminals for connecting gadgets, but these are usually 12V, it would be easier to have 2 meters, you can get something like a Rayleigh for less than £20.

Might be worth talking to https://www.spwales.com

 

[ProDave]

Let me explain better what I am trying to achieve.

I have an air Source heat pump that is providing the heating and hot water for my house.  I would like to keep a track of how much electricity it is using.  So simple, fit an electricity meter.

BUT I would also like to split that down into separate readings for heating the hot water, and heating the house.

I only have ONE load to meter, the heat pump.  So can't use separate meters.  The DIN rail ones would be okay, but same issue, one load = 1 meter = 1 reading.

Then I had the eureka moment. I have the voltage signal that drives the motorised valve that switches it over from heating to hot water. I could use the signal from that to switch a dual rate meter over, so say it would clock up on the A rate while heating the house, and clock up on the B rate while heating the water.  I might need to use a relay to interface my switching signal, no big deal.

So an old school dual rate meter from the days when the time clock was a separate item is what I am looking for, but so far have not found anyone selling one.

The issue is metering ONE load, and switching with a signal from rate A to rate B  If anyone has another solution?

I don't suppose Miss Sweeden is reading and one could fall off her van?

 

[IzzyS]

Why not use two meters and use your hot water signal to switch one or more contactors to switch from one meter to the other?

 

[ProDave]

Why not use two meters and use your hot water signal to switch one or more contactors to switch from one meter to the other?

Because that is a clumsy solution.

If I am forced to a 2 meter solution, then 2 din rail current transformer meters, and switch one current transformer between the 2 meters.

But I know the meter I want exists, probably thousands of them have been scrapped as the DNO's gradually upgrade to the ones with an inbuilt radio teleswitch.  All I want os for one of those scrap ones to become available somehow.

 

[IzzyS]

I only have ONE load to meter, the heat pump.  I don't want to use separate meters. 

I missed that bit 

 

[Sharpend]

Well Dave as it appens i is going to London this weekend, I’ll drop in the science museum and see if they have a spare 

 

[Tony S]

A single meter in the heat pump circuit is all you need. Deduct the reading from the revenue meter.

Other than that I’ve got the drawings for an Ayrton & Perry gaining clock joule meter.

 

[ProDave]

No you are missing the point, I will try again to explain it.

The heat pump will us electricity. I want to know how much. But it is not that simple.

Sometimes the heat pump will be heating the hot water. Sometimes it will be heating the house. It never does both at the same time (different heating temperatures)

So I want to record on one dial how much electricity it has consumed while heating the house, and on the other dial, how much it has consumed while heating the hot water.

So I need a dual rate meter of the type that uses an external input to switch from rate 1 to rate 2.  Think of it not as 2 rates, but dial A and dial B if that makes it easier to understand. 

 

[binky]

so use 2 meters and subtract one reading from the other.

Now I've just been reading the manual for an Elster A1100c dual rate meter, it doesn't count kWh at each tariff it counts 'time' in each tariff band and a cumaltivel kWh - so you would have to work out the kWh used at each tariff yourself anyway.

 

[ProDave]

But I can't easily use 2 separate meters, I only have one thing to meter (plus a switching signal)

Like I keep saying, an old school E7 meter the sort that had an external time clock would do it. At "rest" it would record all usage on one dial, and 

when the "off peak" input was activated (normally by an external time clock but in my case a different switching signal) it would record all the usage on the other dial.

Just where can I get one from?

 

[Evans Electric]

I can offer :-

Westwood Meters & Timers 

Universal Meters

Stephen P Wales      (  Good for seals too ) 

 

[Ardet R]

I think the landis and gyr 5235D has an external time switch for two rates.

On a quick google this place says they have them but they are often not actually the D variant, but might be worth asking them to ensure it is the one advertised.

 

[ProDave]

I think the landis and gyr 5235D has an external time switch for two rates.

On a quick google this place says they have them but they are often not actually the D variant, but might be worth asking them to ensure it is the one advertised.

That has to be worth a look, I will contact them and see what they say.

In the mean time I might have found one.  I have contacted several of the regulars selling them on ebay to ask if they have the type I want, and one has replied back offering an old one with a spinning disk, I am waiting to see how much he wants but I guess it would do.