Help with a relay box rewire

[HRP123]

John will probably be along with the data but I see no real reason for doing this.

Can’t see any big savings to be made. The hot water cylinders need x amount of energy to heat, the house has heat losses and needs y amount of energy to heat.

Hot water priority/range rating aren’t going to change the energy needed.

That is what I originally thought but the problem is when set to a higher total output the boiler does not modulate down well enough when only a few circuits are open.

 

[HRP123]

And then inflation rises again so everything is 15% more expensive etc

Yep, for boilers ... although I wonder if graduallly declining demand for gas boilers will constrain price rises. I think the price of heat pumps will come down with greater production / installation capacity and perhaps even govt support.

 

[ShaunCorbs]

I don’t think it will for at least 10 years

 

[gmartine]

You can't have both if that's what you're implying, once the heat pump market is more established and competition affects pricing government support will be withdrawn as that is the nature of support as the market takes hold.

In your case I think it's a false economy waiting to upgrade considering the many thousands you've been paying to heat your place with a malfunctioning system/design and elderly boiler. All the tinkering in the world won't get the system performance to where you want it to be and I'd expect any upgrade outlay made soon you'd get back in reasonable time considering the size and demands of your system.

 

[HRP123]

Thanks for your thoughts. I'm trying exactly how the savings will come from spending on a potential boiler upgrade -

Presumably the gains from a new boiler are
1. Slightly higher efficiency ratio
2. Lower minimum kw burn rate (between 2-3kw vs current 9kw)
3. Weather compensation (but is this possible with modern heat only boilers? - see below)

Are these modern heat only boilers able to have different flow temperatures for hot water vs heating circuits? If these new boilers still need mixing valves for the heating circuits?

I've seen that the Viesmann 200w is highly recommended however this comes with a more expensive capital outlay and it appears fewer engineers who work with them. The WB Life would be easier to fit and cheaper but has a higher min kw (around 3kw I think).

I'm already in the process of installing all Nest thermostats so I can control and manually adjust things as easily as possible. Have been running the boiler successfully range rated down to around 24kw instead of 40kw. I've just installed an Eddi to make use of solar excess from the recently installed solar panels.

The main issue I find is that the minute the underfloor heating (only) calls for heat, this seems to burn a much higher amount of gas (based on 30 min meter reads) than what the theoretical value should be. So lets say the u/f heating area open is 100m2 x 100w = this should be 10kw right? The boiler almost always will burn close to the max (e.g. 20-24kw) when trying to satisfy just this need.

 

[ShaunCorbs]

As your on ufh you want the lowest possible kw

4 pipe with the viessmann 200 system allows your cylinder to heat to 65 and one circuit to be what ever you want temp wise

The Worcester you need a system boiler with the optional diverter kit

A heat loss is the only way but I would be surprised if you needed over 20kw

 

[HRP123]

As your on ufh you want the lowest possible kw

4 pipe with the viessmann 200 system allows your cylinder to heat to 65 and one circuit to be what ever you want temp wise

The Worcester you need a system boiler with the optional diverter kit

A heat loss is the only way but I would be surprised if you needed over 20kw

Do you have a strong view yourself on whether the Viessman is worth the extra £500-1,000 installed over the WB?

 

[ShaunCorbs]

For the modulation I would go with the better one eg lower kw but Heatloss the property first

 

[HRP123]

For the modulation I would go with the better one eg lower kw but Heatloss the property first

I have actually done the Heatloss - it showed 20kw.

 

[ShaunCorbs]

Do you have cavity wall insulation?