Dear community,
long time reader, first time poster, please be gentle
Quick Summary:
Our company shares a building with another business. The landlord distributes the gas bill based on area size, and since we rent 76% of the building, we pay the majority of the cost.
However, this distribution is unfair because our actual gas usage is much lower. Although we occupy the largest area:
Our production is heated with separate gas burners that have their own meters.
Our offices primarily use air conditioning units running in heat mode.
Out of 21 office radiators, only 4 provide any heat.
There is a very noticeable temperature difference when crossing into the other company’s space, suggesting they use more heating. The landlord won’t change the billing method unless he can measure our specific energy consumption.
We already use Home Assistant to verify the electricity charges. Now, we want to track our heating usage.
Questions:
Can a heat meter + two temperature sensors accurately measure our heat usage?
Can this data be easily integrated into Home Assistant?
I do not know enough about heat pumps to help you, but I can see that there are some details that are not clear to me.
What are the air conditioning units? Are they air to air heat pumps, or do these use water heated by gas?
Does this mean you and the other occupier of the building share a gas boiler producing hot water, and the nett heat emitted into your space is the quantity you want to measure?
I realize I haven’t expressed myself clearly.
We have both a gas boiler, provided by the landlord, which heats water to the radiators, and air to air heatpump units that run on our electricity.
Correct, these radiators warm water is the energy I want to measure.
If you’re sharing one gas boiler with another company, it does sound as if you will need a heat meter to measure how much heat you’re extracting into the radiators in your part of the building.
I think you’ll also need a second heat meter, either to measure the heat going to the other company, or to measure all of the heat output from the boiler from which you can subtract the amount you’re using, to calculate what proportion of heat you are responsible for.
If it’s just for billing purposes, you might get away with reading the two heat meters manually, but it would be sensible to get meters with a Meter-Bus (M-Bus) interface that could also be read automatically. You will need some sort of M-Bus adaptor device to enable that - check for how other people have integrated M-Bus with Home Assistant. There are various options, but it depends on whether you want to pay for an off-the-shelf commercial M-Bus adaptor or are happy to assemble something yourself.
The idea is to see how many kWh of gas were used in total, and subtract the heat we used on our radiators.
This is the other company’s share.
The gas is used by us only for the radiators; our sanitary water is from an electric boiler also.
That would definitely work in your favour, because the other company would be paying for the boiler inefficiency.
Do you mean current transformers?
Why do you need them? You are already measuring your electricity consumption, you do not have an air-to-water heat pump so you are not interested in the ratio of heat out to electricity consumed by this. And in any case, you cannot easily measure the performance of your air-to-air heat pumps.
All you need to measure is the flow of hot water and the temperature difference between the water coming into your part of the building and the temperature of the water leaving.
As I wrote, the kit is designed for an air-to-water heat pump, and to be able to compute the efficiency, and hence be able to adjust the settings for optimum comfort, or cost (or both?) you need to know the electricity consumed, both by the heat pump itself and any circulating pumps.
Idiot me, I haven’t seen the options properly.
Now that I looked at them I see different options for heat meters.
I imagine I will need the bigger one, no? my tubes are DN50
You probably need to find what the rating of the boiler is, either in kW or litres/minute (or both), then estimate what you need from knowing this.
But the largest heat meter in the OEM Shop has DN20 or DN32 fittings (only 16% or 41% of the area, depending on which part of the page you look at!) so I think the pressure drop across this heat meter would be too high. However, downloading the Kamstrup data sheet shows a version with DN50 fittings is available, so you should investigate this. Meanwhile, @TrystanLea, will our heat meter work with to DN50 option of the Kamstrup Multical 403? I assume connections and data format will be the same, what about numerical overflow etc? And if @Oinq needs to order it directly, which options?
After many years in the electrical & electronics industry as a systems/projects/applications engineer, I know only too well that you must always read the data sheet, and anything else that might be in any way relevant. But often more importantly, you must look for the things the data sheet does not tell you - because they don’t want you to know! Then you ask the awkward questions.
560kW if I see correctly? This used to warm a full factory, now it warms 30 radiators in offices…
It’s definitely in our favour, push that (in)efficiency to their side
There are several outputs on this room, the majority of them closed because we don’t feed the big factory building anymore. The majority of the radiators in the factory was removed.
I see 3 pairs of tubes coming to the “newer” side of the building. One is probably the douches from the factory, the other 2 for the offices which were build in 2 phases. We are phase 2, the other company is phase 1. Much probably, reducing it will only impact our radiators, which we almost no use anyway
But we should do this the best way we can.
If a DN50 heat meter exists, it’s better to use it. Now, software wise this also needs to work. I don’t believe this will be a problem?
The disadvantage there is @Oinq’s firm will then have to pay their share of the losses too, and as that boiler appears to be significantly over-sized for its present duty, those could be significant. In any case, a second heat meter should surely be for the other occupier and the landlord to decide?
Maybe a silly question @Oinq, but since you now only use 3 radiators and are getting a big chunk of the total bill, is it possible for you to just disconnect entirely from this boiler arrangement and install your own heaters for these 3 rooms?
Make a clean break. You could then forget about monitoring/ metering “your” portion of the boiler output…and all the disputes that will probably be caused.
Installing a new boiler forces a second gas installation to the building on a separate meter. That plus a small boiler will be the most expensive option; probably only digging a new tube to the building costs above 5000€.
We tried stop using at all in an honor base, the landlord says we can’t accept it because he has no way to be sure we are not using one or 2 without them knowing and it wouldn’t be fair to the others. He can however lock a valve that exists near the dividing wall. Its where I plan to place the meter.
An airco installation would cost 10 000€
I was estimating that installing a heat meter would cost 1000€, now I see that this big boy alone costs that, but it’s still under 2000.
We paid in January more than that in gas.
I still believe the less expensive way to fix a problem that is not ours is the heat meter.
