Harlequin HeatStream - opinions?

[Piers]

Has anyone come across a product called HeatStream made by a company called Harlequin Plastics?

 

Our hot water cylinder & immersion needs replacing and British Gas' contractor (we've got their boiler cover) is trying to flog us an "upgrade".

 

My natural reaction to is usually to tell them where to stick their latest overpriced gizmo. However this product has piqued my interest.

 

I'm not going to claim to fully understand how it works or whether it's effective or efficient. Here's a link to one of their videos: 

 

I like the idea of mains-pressure hot water and I think that the "Twin" version can be heated by gas boiler, solar thermal or a heat pump, as well as the built-in immersion heater.

 

One concern is that the flow-rate is 15l per minute - not ideal for 2 simultaneous showers? 

 

Another worry is the amount of energy required to heat this and heat loss. I can't tell if it's efficient?

 

Any views on this? Latest greatest thing? Dudley McDudface? Or somewhere in between?

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[ProDave]

Sounds to me like a thermal store that has the disadvantage of needing to store water at a hotter temperature, so not much good for example for a heat pump.

[dpmiller]

We discussed it a year or so ago and opinions were mixed. I'm pretty much decided on one regardless...

[Piers]

4 minutes ago, dpmiller said:

We discussed it a year or so ago and opinions were mixed. I'm pretty much decided on one regardless...

 

What's swung it for you?

[dpmiller]

in the flesh they're a very neat solution. Harlequin are well respected locally, and it doesn't require the massive amounts of glycol my other favoured option  (Copper industries Maxipod) would have required.

[ProDave]

55 minutes ago, dpmiller said:

in the flesh they're a very neat solution. Harlequin are well respected locally, and it doesn't require the massive amounts of glycol my other favoured option  (Copper industries Maxipod) would have required.

How are you going to heat it?  Obviously not an ASHP?

 

With a true normal unvented cylinder, it is full of potable water and the only glyvol is in the pretty small closed heating loops.

[dpmiller]

Yes Dave. It's a TS and I'll be dumping energy in from PV, ASHP and a boiler stove. I'm willing to risk the COP losses in getting the water up to 50C or so as it'll still be cheaper than oil and we don't have a mains gas option. Plus E7 is cheap in NI and the timing works well with our lifestyle.

[ProDave]

1 minute ago, dpmiller said:

Yes Dave. It's a TS and I'll be dumping energy in from PV, ASHP and a boiler stove. I'm willing to risk the COP losses in getting the water up to 50C or so as it'll still be cheaper than oil and we don't have a mains gas option. Plus E7 is cheap in NI and the timing works well with our lifestyle.

An ASHP will do 50 degrees, I have mine set to 48 degrees.

 

BUT 50 degree water in a thermal store, will give you very little decent hot water.  With a thermal store, as soon as you start drawing heat from it, the temperature will start falling.  So to maintain a sensible amount of hot water at say 48 degrees, the water in a TS will need to be a lot hotter than that.  On the other hand, fill a UVC to 50 degrees, and it will deliver 50 degree water almost up to the point it runs out then it goes cold very quickly.

 

[joe90]

I’m with @ProDave on this one, I have virtually the same set up as Dave, my ASHP delivers 48’ water and that is fine fir all out hot water needs without the need to heat a thermal store to above this temp. I have never seen our ASHP defrost yet (been in six months thro winter).