DPS Thermal Store- hot water/flow issues

[Zippymark]

Hello, hope you're all enjoying the bank holiday weekend.

I have a customer with a Dedicated Pressure System (DPS) Heat Bank System (Thermal Store).

If they run one bath/shower, it's fine. If they try to run two at once the water at both is barely even warm.

I know the house has been extended by about 50%, adding an additional bathroom that the thermal store was not originally installed to cover.

I'm unsure if there's any fault involved, or if the flow rate of two showers at once is just exceeding the max flow rate that the thermal store heat exchanger can keep up with. The thermal store capacity is 150ltrs, my gut feeling is this just isn't up to the job, though i guess there could be a few issues with it causing it to not perform at full spec (pump running slow, blocked heat exchanger etc)

Has anyone got much knowledge of these and can advise whether it's worth investigating or if it's just not big enough?

Thankyou in advance for any help

 

[SJB060685]

Whats the store temp set to?
And what's the rough final temperature with both outlets open?

 

[Chuck]

I'm unsure if there's any fault involved, or if the flow rate of two showers at once is just exceeding the max flow rate that the thermal store heat exchanger can keep up with. The thermal store capacity is 150ltrs, my gut feeling is this just isn't up to the job, though i guess there could be a few issues with it causing it to not perform at full spec (pump running slow, blocked heat exchanger etc)

Has the system ever worked since the extension was installed? I'd measure the flow rates (with a jug and stopwatch) and temperatures for the two cases and then compare these with the manufacture's specs.

Even a single plate HX on the current version of these systems can supply 30 litre pm of hot water, which should be enough to supply a couple of reasonable showers.

Once you've made some measurements, either post them here or contact DPS, who are still in business and have after-sales tech support.

 

[Zippymark]

Whats the store temp set to?
And what's the rough final temperature with both outlets open?

It was a little low i think at 60 so i put it up to 70.

Both outlets open i'd say 25/30 degrees, barely warm at all

 

[Zippymark]

Has the system ever worked since the extension was installed? I'd measure the flow rates (with a jug and stopwatch) and temperatures for the two cases and then compare these with the manufacture's specs.

Even a single plate HX on the current version of these systems can supply 30 litre pm of hot water, which should be enough to supply a couple of reasonable showers.

Once you've made some measurements, either post them here or contact DPS, who are still in business and have after-sales tech support.

I'm not sure as the current homeowners have only been there for a short while, but hasn't worked adequetly in the six months they've been there.

And i didn't realise they were still about, sounds like i need to go back and do a more detailed investigation, if this has the same flow rates as that then it should be able to keep up.

It was just one of those jobs that i didn't want to spend an hour or so measuring things if it was all going to be a waste of time anyway

Thanks for your reply

 

[SJB060685]

As Chuck has said above looking at the data this unit on a single PHX should be more than capable of supplying up to 30 LPM at 45°c at a store temperature of 80°c.

 

[Chuck]

And i didn't realise they were still about, sounds like i need to go back and do a more detailed investigation, if this has the same flow rates as that then it should be able to keep up.

I believe that they are now:

Commercial Heating Solutions | Heat Networks | Heatweb

Heatweb - UK leaders for commercial heating solutions, heat networks & more. We support projects with pioneering technology for precision heat performance.

www.heatweb.co.uk

 

[SJB060685]

The data sheet I found is blurry on the graph which represents achievable flow rates with respect to store temp. Its also blurry on the graph depicting flow rates from KW output of the PHX from a set incoming temperature and temperature rise.
I would increase the store temp to between 70 and 80°c and see what happens. I suspect with the store temp at 60°c you weren't getting anywhere near the KW needed for your high demand flow rates.