BTu meters

[Besoeker]

A customer of ours has asked us to quote for and supply BTU meters to check the heat loss in cooling water.
Technically it doesn't sound too demanding and, since we make water-cooled high current rectifiers, we would have the necessary electrical and plumbing skills to undertake the work. It isn't something we've done before - BTUs haven't been used a a unit here (UK) for a long time. I think gas bills (as in cooking gas) used to be in BTUs but now, like the electrical energy bill, it is in kWh.

So, if anyone here has any experience of using, fitting, or supplying BTU meters, I'd appreciate any input.

 

[MEP_PM]

I haven?t seen BTU meters installed on single pieces of equipment. What size are your cooling pipes? The meters I have seen installed were on 3-4? pipes and larger. It is not uncommon for BTU meters to be installed on a large heating or cooling system to monitor energy usages. And sometimes a large campus (Healthcare & Universities) will installed BTU meters on the buildings so the Facilities Dept can charge the building/department for their usages of the Campus System. ONICON meters (www.onicon.com) were used on several recent projects. They seem to be pretty easy to install and set up. Make sure you locate the flow meter in a length of straight pipe as recommended by the manufacture and that you have enough room to install the flow meter on the pipe. Also make sure you buy a meter with the correct flow range, temperature ranges and communication outputs.

 

[Besoeker]

I haven?t seen BTU meters installed on single pieces of equipment. What size are your cooling pipes? The meters I have seen installed were on 3-4? pipes and larger. It is not uncommon for BTU meters to be installed on a large heating or cooling system to monitor energy usages. And sometimes a large campus (Healthcare & Universities) will installed BTU meters on the buildings so the Facilities Dept can charge the building/department for their usages of the Campus System. ONICON meters (www.onicon.com) were used on several recent projects. They seem to be pretty easy to install and set up. Make sure you locate the flow meter in a length of straight pipe as recommended by the manufacture and that you have enough room to install the flow meter on the pipe. Also make sure you buy a meter with the correct flow range, temperature ranges and communication outputs.

Thank you kindly. The application is pretty much as you describe. Cooling water on a HVAC system as far as I can tell.
I had already looked at Onicon - it was the first hit on the search engine.

And I have asked our salesman dealing with this to get more and better detail.
A couple of exchanges...

From me:

To compute the energy we?d need temperature difference between inlet and outlet of the water and flow rate.
This would require field mounted transducers so it moves away from being ?just? a meter unless such transducers already exists or the customer intends to fit them.

There are standard products available. Perhaps that should be kits of parts if we need to supply/fit the transducers.
It?s a plumbing/electrical installation. We need expected ranges for flow, temperatures, energy, locations, pipe sizes...etc

The numbers of installations make it look like an attractive opportunity. Being two or three steps removed from the end user makes obtaining specific information hard work. Particularly if those in between don't understand/have no clue about what they are dealing with.

A new piece of information came in since I last posted. The output from the instrument is required in kWh. Fine. I can convert BTU to kWh. The next question is whether a measurement in BTU is actually relevant in the first place. Sticking with SI throughout would obviously be simpler.

I appreciate your input and I'm sorry if I sound grouchy. Been a long day and I'm being asked for stuff without sufficient data to put forward a credible professional response.

 

[Electric-Light]

I seem to recall that due to many variable factors, revenue grade steam energy meter used by utility to bill customer for steam use is quite complicated. The pressure, temperature, density, etc changes thermal capacity, so flow * delta T gets you a pretty good idea, but not good enough for billing purpose.

For your rectifier system, you could use a two channel power analyzer and take the difference and voila, you have the exact thermal dissipation.

From there, you could just assume the rectifier as a heating element and check the temperature change. Sure, there's a slight thermal capacity difference between near freezing and near boiling water, but you're not selling the energy, so you don't need anything close to revenue grade thermal meter.


BTU is a quantity, like kWh, or gallons.
BTU-hr is a rate of flow like kW and GPM.

BTU-hr and kW can be converted in between on a calculator.

It doesn't matter what unit you use. The only road block is if you have to have the user interface display in a unit not commonly used. Then, you'll need to change the scaling or use software.

 

[Besoeker]

For your rectifier system, you could use a two channel power analyzer and take the difference and voila, you have the exact thermal dissipation.

It isn't our rectifier system. Had it been I would have worked out the dissipation from the characteristics of the SCRs. In fact, I would have done that at the design stage before anything was built in order to size the various components. There's no quick fix if the get the calculations wrong on a 40 kA system!
Anyway, as I noted in post #3, I think it is for a HVAC system.

BTU is a quantity, like kWh, or gallons.

Well, being British myself, I have a pretty fair idea of what a BTU is........

BTU-hr is a rate of flow like kW and GPM.

That would be BTU/h to get the rate rather than BTU-hr

It doesn't matter what unit you use. The only road block is if you have to have the user interface display in a unit not commonly used. Then, you'll need to change the scaling or use software.

As I posted earlier, the customer wants an output in kWh so it may be possible to keep it all in SI units and avoid the conversion. It would make things simpler.