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d0 is the max KW output of the boiler and should be set to the heat loss of the house. The boiler will modulate down automatically, though, so if the radiators are not getting warm, then you may have a circulation problem and the boiler may be shutting down prematurely. I'd observe the boiler...

Is it definitely the unvented cylinder EV (usually white in colour) and not the central heating EV (usually red)? If so, the EV needs to be suitable for potable water, which is why it will be more expensive. As said already, try having the vessel recharged and see if it holds pressure. I don't...

If the bubble is depleted, there will be no room for the expansion of water as it heats up. This will result in a discharge from your pressure relief valve (a safety feature) everytime you heat your cylinder, which is far from ideal. An alternative is to fit an external potable expansion vessel.

I think his point is that on a Megaflo tank, with an internal expansion bubble, the recharge procedure involves opening the Pressure Relief Valve.

You'd get a mix of cold and hot, adjusted automatically if using a thermostatic shower. You could reduce the temp on the shower to use less hot, or you could increase the temp of the cylinder to allow you to use less hot at the same shower temp.

The pump should come on with your boiler and will most likely also run for a short period of time once the boiler stops firing. The I, II, III settings increase the pumps power (and therefore electricity usage), and depending on the size of your system and the layout, you may need the highest...

Did you try this? If this works, you can then try II or even I, and see which works best for you. Was the pump working previous to the Hive install, and if so, which setting was it on? The hive will make no difference to the performance of the pump, so the setting must have been changed if it...

There's only 2 options: 1. upgrade water main to get more incoming flow 2. have some form of stored water For (1), upgrading just the supply pipe which belongs to you may or may not be enough. You can ask your water company to measure the flow at your roadside boundary to see if this would be...

Keep in mind the actual usable capacity of an accumulator: Using Precharge = lowest dynamic pressure, Vessel volume V and Static Mains pressure M, (all pressures as measured on gauge) Stored volume is given by V(1 - (P+1)/(M+1)) Read more...

Have a search on the automated home forums, I believe this has been discussed quite extensively: https://www.automatedhome.co.uk/vbulletin/forumdisplay.php?13-Heating-Control

Sounds fine. I did similar - but I did away with the 22mm PRV altogether and replaced with a 28mm Reliance.

So I think what you're saying agrees with what myself and JohnD said. In my previous post, I used the phrase "increase flow" quoted here: Let me clarify that - I should have said increased flow at the outlet - ultimately, we are talking about increasing flow at a basin or more typically a...

Dan, I'd be interested to hear why you believe this would not work? I don't want this to descend into an argument over who knows better, as many threads do, but rather genuinely intrigued to the answer. For my part, all of the reading I've done on the subject says that reducing the pipework...

Really? Do you think it makes any difference if the severe restriction is at the beginning or the end of the pipe run? Edit - fixed typo make to makes

As JohnD said - that's not how it works. You can increase the pipe diameter at any point in the run to reduce resistance and improve flow.

If it stops the boiler from overheating, then i'd say it's served it's point.

As I've learned (from painful experience) - the minimum flow rate may well be required because of the high output of Vaillant boilers in the first 30/40 seconds, regardless of if they modulate down after this time. If minimum flow rate is not maintained for those first 40s, you'll probably hit...

Yes, there's hydraulic separation. There will be mixture in the chamber of a LLH, but the important part is that the resistance of the boiler no longer needs to be taken into account when sizing the pump for the CH system. Since installing mine, the boiler is far happier and maintains its approx...

That's precisely what they do. The boiler side of the LLH/CCT has it's own pump responsible for overcoming the boiler's HEX resistance (and any minimal pipework), whilst the CH side has one or more pumps to overcome the resistance in the individual zones.

I found the 22mm megaflo pressure reducing valve was severely restricting flow in my house. I, too, had a 32mm mdpe coming in. I had a g3 plumber upgrade the prv to a 28mm reliance valve (along with the pipework from the mdpe to the prv) and it made a dramatic difference in flow rate to my...