Puzzled by new type of central heating boiler featured in the Guardian today

[urbanspaceman]

First microwave-powered home boiler could help cut emissions

‘Drop-in’ replacement for gas boilers may help tackle the challenge of cutting climate emissions from home heating

www.theguardian.com

A new way to transform how we heat our homes | Heat Wayv

A new way to transform how we heat our homes Microwave boilers: replacing the world’s gas boilers to meet the Net Zero target for carbon emission

www.heatwayv.com

There's a story about the "Heat Wayv" boiler in the Guardian this morning. It apparently heats the water in the CH circuit using microwaves. I can't understand what the advantage is over straightforward resistive heating.

Am I missing something ?

The price will be £3,500, which they claim is about the same as the equivalent gas boiler. Which is nonsense - my last boiler cost about one quarter of that.

 

[Pickman's model]

First microwave-powered home boiler could help cut emissions

‘Drop-in’ replacement for gas boilers may help tackle the challenge of cutting climate emissions from home heating

www.theguardian.com

A new way to transform how we heat our homes | Heat Wayv

A new way to transform how we heat our homes Microwave boilers: replacing the world’s gas boilers to meet the Net Zero target for carbon emission

www.heatwayv.com

There's a story about the "Heat Wayv" boiler in the Guardian this morning. It apparently heats the water in the CH circuit using microwaves. I can't understand what the advantage is over straightforward resistive heating.

Am I missing something ?

The price will be £3,500, which they claim is about the same as the equivalent gas boiler. Which is nonsense - my last boiler cost about one quarter of that.

Guardian readers pay a premium on gas boilers

 

[two sheds]

It puzzled me, too. They describe it as being able to provide 'zero-emissions' replacement which is clearly bollocks.

They say the boiler is 84% efficient in converting electricity into hot water, and another 12% of waste heat is recycled, giving a total efficiency of 96%.

An immersion heater is probably going to have that sort of efficiency isn't it? The heat leaking from my immersion heater goes to heat upstairs, too.

 

[two sheds]

I much prefer the idea of the wind generating vibrator they've covered elsewhere today.

 

[killer b]

I think the advantage is that it uses electricity, which can come from a renewable source, not gas, which can't

 

[urbanspaceman]

I think the advantage is that it uses electricity, which can come from a renewable source, not gas, which can't

Yes, but so does a simple resistive heater. And resistive heating works at about 100% efficiency too. I just don't get it.

 

[two sheds]

True, although gas can be recovered from waste etc. It's only zero emissions in the sense that electric fires are zero emissions.

^^ what urbanspaceman said

 

[killer b]

oh, ok. I thought you were comparing with gas

 

[Fez909]

I think the advantage is that it uses electricity, which can come from a renewable source, not gas, which can't

Renewable natural gas - Wikipedia

en.wikipedia.org

 

[Winot]

Is the difference to an immersion heater that it provides hot water on demand (like a combi)?

 

[urbanspaceman]

Electric Boilers | Central Heating | Screwfix

Buy Electric Boilers at Screwfix.com. Electric powered alternative to gas. Domestic & commercial use. No emissions. Trade trusted. Delivery 7 days a week.

www.screwfix.com

Yes, just like these do. Heat Wayv costs three times as much and cannot be more efficient.

 

[Crispy]

Is the difference to an immersion heater that it provides hot water on demand (like a combi)?

Yes, I imagine the advantage is that it's more responsive. A resistive heating element takes time to heat up, and has to heat itself as well as the water. Microwaves are "instant-on" and only heat the water.

Saying that, the priority should be improving the thermal efficiency of existing homes such that they can be warmed with a heat pump, which is far more efficient than hot water radiators.

This thing would then be useful for the buildings that aren't suitable for heat pumps.

 

[two sheds]

Yes, I imagine the advantage is that it's more responsive. A resistive heating element takes time to heat up, and has to heat itself as well as the water. Microwaves are "instant-on" and only heat the water.

Saying that, the priority should be improving the thermal efficiency of existing homes such that they can be warmed with a heat pump, which is far more efficient than hot water radiators.

This thing would then be useful for the buildings that aren't suitable for heat pumps.

Is this for on-demand only then, rather than an immersion tank so you've got hot water all the time?

Even better for suitable houses would be pv panels with a controller to take the excess electricity to heat the immersion heater - has worked really well for me. Get hot water most of the year round.

I'm really tempted by an air source heat pump for space heating. House is old and probably quite leaky but I've added insulating wallpaper and secondary glazing. I only really need heating for three/four months of the year, and only really for upstairs - that's the only place I really feel cold. At the moment I put a 1kW electric fan heater on upstairs, and it appeals to have a 0.3kw heat pump on for the 1kW output.

I've heard heat pumps aren't generally good for non-airtight type houses though, and also probably not good for repayment times.

 

[WouldBe]

Just been looking at this. I think the advantage is that you use less power with microwaves than with resistive heating just look at cooking times in microwave ovens compared with conventional ovens let alone the difference in power consumption between the two.

 

[urbanspaceman]

Just been looking at this. I think the advantage is that you use less power with microwaves than with resistive heating just look at cooking times in microwave ovens compared with conventional ovens let alone the difference in power consumption between the two.

But since resistive heating is close to 100% efficient, given that the heating element is immersed in water, how can a microwave heater be even more efficient ?

 

[platinumsage]

The current solution is "inline electric water heaters" which for domestic use are available up to 12kW e.g:

Redring Unvented Instantaneous Water Heater - Powerstream - 12kW7 RP12

Hot water supplied to one or two outlets, with water outlet via existing tap or mixer (especially suitable via spray tap).

www.aquahot.co.uk

The problem with these is that the element tends to burn out quickly if you put too much demand on it (i.e. turn the hot tap on in the kitchen when someone is having a shower). So they're really not suitable for more than one-bedroom flats, let alone asking them to supply central heating radiators too.

Could the microwave boiler improve on this while being a direct replacement for a gas combi by running off a 13 amp supply? The main barrier apart from physics would appear to be that domestic microwaves only last a few thousand hours before dying. They'd have to improve on that or else these boilers would only get you through a couple of winters.

 

[Shippou-Sensei]

But since resistive heating is close to 100% efficient, given that the heating element is immersed in water, how can a microwave heater be even more efficient ?

 

[farmerbarleymow]

I've always been interested in basically turning the interior of a house into a a microwave oven for true microwave heating. Has some downsides though, like cooking your bollocks.

#1040: The brave new world of microwave home heating

If Adair's microwave addicted monkey junkies are not enough to strain credibility (last message) then how about the insanity dreamed up by her IEEE standard setting buddies Buffer and Osepchuk which Adair referred to in the NYT article. Check it out in New Scientist, 21-28 December 1996. The followi

www.emfacts.com

 

[NoXion]

Wouldn't microwave heating a home(!) also present issues with regards to metallic objects and electronic devices? Turns out it does. I can't say I'm terribly excited by the prospect of having an active and unshielded 800-watt microwave source right under my roof that could burn me if I picked up something metallic. Oh yeah and the spinny metal things to prevent the formation of hot spots sound like a maintenance and logistical pain in the fundament.

Not as daft an idea as the enriched uranium codpiece, but it hardly seems practical either.

 

[farmerbarleymow]

Wouldn't microwave heating a home(!) also present issues with regards to metallic objects and electronic devices? Turns out it does. I can't say I'm terribly excited by the prospect of having an active and unshielded 800-watt microwave source right under my roof that causes me burn. Oh yeah and the spinny metal things to prevent the formation of hot spots sound like a maintenance and logistical pain in the fundament.

Not as daft an idea as the enriched uranium codpiece, but it hardly seems practical either.

Just think though you could get rid of your oven - just walk in the door with your tea and in a few minutes it'd be cooked.

 

[WouldBe]

But since resistive heating is close to 100% efficient, given that the heating element is immersed in water, how can a microwave heater be even more efficient ?

With electric boilers the resistive heating element is not immersed in water it's wrapped around a pipe inside the boiler.

 

[WouldBe]

Just think though you could get rid of your oven - just walk in the door with your tea and in a few minutes it'd be cooked.

You'd have to sit in an 'oven' to prevent being cooked but if you needed to re-heat your coffee you could just open the door and stick your mug out.

 

[urbanspaceman]

The current solution is "inline electric water heaters" which for domestic use are available up to 12kW e.g:

Redring Unvented Instantaneous Water Heater - Powerstream - 12kW7 RP12

Hot water supplied to one or two outlets, with water outlet via existing tap or mixer (especially suitable via spray tap).

www.aquahot.co.uk

The problem with these is that the element tends to burn out quickly if you put too much demand on it (i.e. turn the hot tap on in the kitchen when someone is having a shower). So they're really not suitable for more than one-bedroom flats, let alone asking them to supply central heating radiators too.

Could the microwave boiler improve on this while being a direct replacement for a gas combi by running off a 13 amp supply? The main barrier apart from physics would appear to be that domestic microwaves only last a few thousand hours before dying. They'd have to improve on that or else these boilers would only get you through a couple of winters.

Nobody is suggesting using a domestic hot water heater to power a central heating circuit. Purpose-built electric central heating boilers exist. They cost a lot to run, but they do exist.

Electric Boilers | Central Heating | Screwfix

Buy Electric Boilers at Screwfix.com. Electric powered alternative to gas. Domestic & commercial use. No emissions. Trade trusted. Delivery 7 days a week.

www.screwfix.com

A 13 amp power supply can provide 3kW maximum. A boiler for a typical house is rated at about 10kW. Any sort of electric boiler, immersion or microwave, must be connected to a dedicated high power circuit.

 

[two sheds]

Just been looking at this. I think the advantage is that you use less power with microwaves than with resistive heating just look at cooking times in microwave ovens compared with conventional ovens let alone the difference in power consumption between the two.

Microwaves heat by radiation though which heats the inside of the meat instantaneously, while conventional ovens heat using convection and conduction which take much longer to heat through.

 

[WouldBe]

Microwaves heat by radiation though which heats the inside of the meat instantaneously, while conventional ovens heat using convection and conduction which take much longer to heat through.

So a microwave should use less power.

 

[two sheds]

to heat meat and things through to the centre, yes, it concentrates the heating into the food.

 

[platinumsage]

Nobody is suggesting using a domestic hot water heater to power a central heating circuit. Purpose-built electric central heating boilers exist. They cost a lot to run, but they do exist.

Electric Boilers | Central Heating | Screwfix

Buy Electric Boilers at Screwfix.com. Electric powered alternative to gas. Domestic & commercial use. No emissions. Trade trusted. Delivery 7 days a week.

www.screwfix.com

A 13 amp power supply can provide 3kW maximum. A boiler for a typical house is rated at about 10kW. Any sort of electric boiler, immersion or microwave, must be connected to a dedicated high power circuit.

Yes that's what I meant.

This microwave thing is meant to be a direct replacement for a gas combi, so it will need to heat the radiators as well as provide hot water for e.g. a 3-bed semi.

In-line hot water heaters using 12kW can barely provide for a shower and a tap. So this microwave combi replacement would have to be pretty awesome to deliver what it needs to without an upgrade to the previous gas combi's electrical supply.

My electrician said if you want an in-line electric hot water heater than can cope with a normal 3-bed household, it needs to be more like 27kW.

 

[Winot]

to heat meat and things through to the centre, yes, it concentrates the heating into the food.

Specifically, they work by using a frequency which resonates with the natural frequency of water molecules, so they make the molecules rotate and that’s what heats up.

 

[two sheds]

Specifically, they work by using a frequency which resonates with the natural frequency of water molecules, so they make the molecules rotate and that’s what heats up.

not the natural frequency of chicken molecules?