Measuring Hot Water Consumption in Shared Recirculation System

[lollino]

Hello everyone,

I'm facing a rather complex situation and I need your expert advice. My neighbor and I share a boiler for hot water, and we have a single recirculation pump serving both of our homes. However, after the pump, the recirculation circuit splits into two separate branches, each serving our respective dwellings.

We currently have meters installed on the cold water to track individual consumption, but we lack a system to measure hot water usage. Our plumber claims that we cannot install meters on the hot water due to flow disturbances caused by recirculation.

I'm looking for a solution to fairly and accurately measure hot water consumption in each home. One idea I had considered was to install two meters, one at the entrance and one at the exit of the recirculation circuit, but I am aware of the technical difficulties this might entail.

I would like to know if, given the configuration of our system, a solution could be to install two separate recirculation pumps, one for each branch, and whether this could facilitate a more accurate measurement of individual consumption. Alternatively, are there flow meters or other technologies that can be effectively used in a system with these characteristics?

I would be very grateful for any advice, suggestions, or shared experiences you can offer.

Thank you very much for your time and attention to my request.

Best regards,
Lorenzo

 

[MicEd69]

From your description, I'm assuming you have a circulating system for your hot water and single point users come off that loop. If that is the case, then you would need a meter on each single point user, which is rather impractical.

If you reconfigured the loop into two separate loops, then you could theoretically install a meter going out to each loop and a meter coming back from each loop with the difference being the hot water usage for each home. Again, a little impractical in my opinion.

Of course, you could simply eliminate the circulating pump, reconfigure the piping so that each home would have a single hot water line to it and install a meter at the two points coming from the water heater. Both homes would have to wait for hot water to get the single point users which would waste water, but it could be measured. Again, an impractical "solution".

 

[lollino]

From your description, I'm assuming you have a circulating system for your hot water and single point users come off that loop. If that is the case, then you would need a meter on each single point user, which is rather impractical.

If you reconfigured the loop into two separate loops, then you could theoretically install a meter going out to each loop and a meter coming back from each loop with the difference being the hot water usage for each home. Again, a little impractical in my opinion.

Of course, you could simply eliminate the circulating pump, reconfigure the piping so that each home would have a single hot water line to it and install a meter at the two points coming from the water heater. Both homes would have to wait for hot water to get the single point users which would waste water, but it could be measured. Again, an impractical "solution".

Hello! Thank you very much for your response.

From your answer I tend to understand that you would leave things as they are and split cost with the neighbours, correct? I'm doubtful because they are consuming the double of cold water (I know there's not a direct correlation but...) and we invested in the shower hot water recovering "joulia". Moreover, the constructor told us to wait for the end, wait for the end... and now it's too late to do easy modifications.

Why you consider impractical the option to install a meter on the single hot water outlet? There would be only 7 of them, does exist a very small meter, even manual?

Thank you,
Lorenzo

 

[GReynolds929]

Your water meter measures all water used by you, hot and cold. What is the need for metering hot usage separately? I'm not understanding.

 

[lollino]

Your water meter measures all water used by you, hot and cold. What is the need for metering hot usage separately? I'm not understanding.

We are in a semi-detached house and the heat pump together with the hot water tank are in common with the neighbours!

I would need to know my consumption to split the cost with the neighbours!

 

[MicEd69]

There would be only 7 of them, does exist a very small meter, even manual?

I've not looked at small water meters except in an industrial application. But a quick search looks like the cheap ones have a maximum temperature of 40 C to 50 C. But if you want to spend $75 to $100 for materials alone for each hot water user, then that could work. Every kitchen sink, bathroom sink, shower, tub, washing machine dishwasher, bidet, etc. Some devices may be able to be hooked together, but that depends on the plumbing layout.

Seems like a lot of work and upfront money to save an unknown amount.

How is the water heated and who pays for that?

 

[lollino]

I've not looked at small water meters except in an industrial application. But a quick search looks like the cheap ones have a maximum temperature of 40 C to 50 C. But if you want to spend $75 to $100 for materials alone for each hot water user, then that could work. Every kitchen sink, bathroom sink, shower, tub, washing machine dishwasher, bidet, etc. Some devices may be able to be hooked together, but that depends on the plumbing layout.

Seems like a lot of work and upfront money to save an unknown amount.

How is the water heated and who pays for that?

Well, you'd be very right but my position is that constructor should pay for meters, thus it returns to be cost savings for me. I need to find small meters though. Hot water is produced by an heat pump air/air in common with the neighbours.

 

[Twowaxhack]

Install your own boiler.

 

[MicEd69]

My search didn't find any hot water meters that are for potable use and that are reasonable for this installation. But if this is on the contractor for this installation, contact him and have him do the searching. Relatively low flows for some uses and water quality causing mineral deposits on the hot water side could end up being a maintenance problem.

 

[lollino]

My search didn't find any hot water meters that are for potable use and that are reasonable for this installation. But if this is on the contractor for this installation, contact him and have him do the searching. Relatively low flows for some uses and water quality causing mineral deposits on the hot water side could end up being a maintenance problem.

Thank you!

The constructor is not that propositive thus I would reccomend him what to do basically.

Thanx for the advice on deposits, will have a look!

 

[Mitchell-DIY-Guy]

…the recirculation circuit splits into two separate branches, each serving our respective dwellings…I'm looking for a solution to fairly and accurately measure hot water consumption in each home.

Look here:

https://www.flows.com/wm-nlch-series-hot-potable-water-meter/
This is a potable hot water meter, (what you want) designed for “sub-metering” (also what you want). The listed flow rates seem to be well within normal usage.

It is designed for US standards in terms of measurement (gallons etc.) and fitting (pipe sized in inches). The former should not be an issue since you could use any measurement to determine usage per flat versus total but the USA pipe size may pose a problem in Switzerland.

Contact the company for more specifics on fitting into your home’s plumbing.

 

[lollino]

Wow! Thanx very much!!!