Is this unique to Alpha?

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On the Alpha regular boilers, it looks like you can buy a relay board which lets you set a higher flow temperature when there is a DHW demand. Both CH and DHW would be at that higher temperature. So you get some of the benefits of priority hot water. I can see it working really well if you have the HW on for an hour first thing before the CH comes on.
 
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They work really well, all regular boilers should have them as standard
 
We are currently finishing a small site using ideal vouge system boilers using hot water priority (X plan)
Working very well.
 
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Anybody know whether this kit is available as an add-on, from a boiler supplier or otherwise? Most likely as a weather compensation package, but still useful if the CH temperature manually set.
 
Alpha sales line told me that they have them in stock. They said to contact plumbers merchant who will ring Alpha to get the price. It's only for the regular boilers, I think, not the system boilers.
 
Anybody know whether this kit is available as an add-on, from a boiler supplier or otherwise? Most likely as a weather compensation package, but still useful if the CH temperature manually set.

Vaillant boiler, plus its controls, does that, but the boiler can obviously only service one, or the other, at any one time. I simply set the heating of my cylinder, to happen an hour before the heating might be needed.
 
Anybody know whether this kit is available as an add-on, from a boiler supplier or otherwise? Most likely as a weather compensation package, but still useful if the CH temperature manually set.

This might be relevant from an article linked by @CBW on another thread. It looks like with many boilers there is a cheap add-on to get two flow temperatures.

https://heatingacademynorthampton.co.uk/pdhw/

Any boiler with WC can be ‘tweeked’ to run PDHW using a simple 5 wire £15 relay, any OT boiler controlling either S or Y can be simply upgraded with no pipework using standard EPH controls.
 
Thanks gents

I have a W-plan system with an On/Off boiler, and I’d like to add variable flow temperature. I envisage something like attached sketch, where the pipestat is manually adjusted depending on outside temperature. That’s quite straightforward to install.

Weather comp would be better, I assume that needs an analog temperature sensor on the flow pipe, along with the switch and outside sensor. I was hoping to see that available as a kit, but having had a good look on the internet I can’t find anything.

I assume on a modern modulating boiler (hence analog flow temperature control) it would need to be set up for possible retrofitting of weather comp, with the necessary terminals. But the installation manuals I’ve looked at don’t mention it. The attachment from Ideal lists their compatible boilers. There are several wiring diagrams labelled Weather Compensation Kit – Installation, but none of them mention weather compensation!

Ideal Weather Compensation Kit
 

Attachments

  • W-plan adjustable temp.pdf
    1.4 MB · Views: 26
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Any good?
Thanks for that. I found there's also now a BEM 5000 (not sure of the difference). I'm not thinking of spending £200, it would take ages to recoup that. Either would work on my old On/Off boiler, but no good on a modern modulating type. For that, need to ensure the kit is compatible with the boiler electronics, most likely by getting it from the boiler supplier.
Discussed at some length in the 14 Oct 22 thread below.
Of course, if you separate HW and CH periods on the programmer, you can have a different flow temperature for each, and PDHW isn't needed.
 
I have a W-plan system with an On/Off boiler, and I’d like to add variable flow temperature. I envisage something like attached sketch, where the pipestat is manually adjusted depending on outside temperature. That’s quite straightforward to install.

Before my present fancy boiler and controls were installed, which allow separate temperatures for HW v CH, I had the same idea for my condensing, but none modulating boiler.

What I found was, it was a total waste of time.......

The ordinary mechanical/bimetal stat, had far too wide an hysteresis (switch on, versus off point), that it would switch off on rising temperature, then the house would cool far to much, before it would click back on. What it needed, was a much more precise means of switching, such as could be provided by an electronic sensor, which had built in adjustable hysteresis. I had several such modules around, but never got around to employing one, before that boiler needed replacing by my present one.

Set the hysteresis too tight, and it would involve extra wear and tear on the boiler, too wide and the house cools too much. Best of all, i proper, separate temperatures, with modulation, and even better, the boiler being aware of how near it is to achieving the desired temperature, so it can throttle back it's output of heat.
 
The ordinary mechanical/bimetal stat, had far too wide an hysteresis (switch on, versus off point), that it would switch off on rising temperature, then the house would cool far to much, before it would click back on.
Your system sounds good, but I'm not quite with you there Harry. I wasn't thinking of controlling room temperature by the boiler control-stat, just reducing the flow temperature to increase condensation. But still hot enough to warm the house until the roomstat is satisfied (as currently).
BTW my control-stat is a filled system (I think is the term for it) not bimetallic. Don't know if it's any better for hysteresis though.
 

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