@chandykris I know people who had had IR panels and they found them effective. My worry would be the running costs, unless you only heat the room you are in all the time. A 500W panel would cost the same to run as my heat pump on a Spring or Autumn day and I would be heating the whole house.

Thanks @bontwoody  

That would be the plan, heat only the rooms that we use and when. We have far too many spare rooms that are sparingly used in the winter. I need to test my hypothesis that IR heating if executed correctly can match our requirements. Even if running costs are the same, if we can cut down on emissions from 7500 kWh gas usage per annum, that would be our motivation. Already hot water (roughly 3000 KWH gas usage per annum) has been switched over to off peak electricity and solar. So, only further 4500 KWH of heating requirement needs to be decarbonised.

@chandykris A noble ambition! I was hopeful my house would be energy positive, but buying an EV has scuppered that 😀 

Your first mentioned zones a lot. Urban plumber heat geeks etc, should tell you straight NO, to zones.

The heat that migrates in to the unheated rooms comes from somewhere when it's cold outside, they don't magically stay above above zero. They take heat from the rest of the house, the rest of the heating system runs slightly warmer to heat the room they are in, and the excess heat that leaks to heat colder indoor rooms. So efficiency takes a hit with a heat pump because you have to flow at a higher temp to the radiator.

You can zone as much as you like, but, you need a buffer to keep the heat pump happy. You are likely to take an efficiency hit. You will run the system a few degrees warmer than one zone would allow, you take an efficiency hit again. You have to run multiple pump because you have a buffer, another efficiency hit. And you wallet will not like you.

A decent install should give you a SCoP of around 4, a well installed zoned system around 2.5 SCoP. A poor one read all the stories in the press.

IR heater.

Great in a bathroom where the quickish response time is good. But they also run for a short time. They are like any other electric panel heater 100% efficient, 1kW in, 1kW out. They are very directional, so you have a warm front and cold back.

Would limit to short bursts. I did consider for quite a while. But your case 7500kWh x £0.25p is £1875.

Your zoned ASHP well installed allowing (7500kWh / 2.5) x £0.25= £750.

Single zone delivering 12000kWh

(12000 / 4) x £0.25 is £750.

But if your 7500kWh is realistic 

(7500 / 4) x 0.25 is £470

7500kWh on gas at £0.05 per kWh and 90% efficiency. Is slightly cheaper at £413.

Realistic system would be 

ASHP, 3 port diverter, heat pump cylinder, single zone, control bedrooms at 18 to 19 degs either by radiators sizing, balancing or trv. Size for 45 or below flow temperature. 

Check your loft insulation and add to the max. Compressed areas will not perform well.

Thanks @johnmo

Yes, have watched a detailed video from HeatGeek on why zoning is not good. So, if we go for heat pumps the heating output would be more like the 12K like you have mentioned. That's close to what we used to consume before we fitted Tado TRVs and thermostats to control gas consumption (and thereby emissions).

We are on a time of day EV tariff, so leverage that to heat the hot water. So, highly unlikely that we would use 7500 KWH at £ 0.25. Hot water part of that usage, around 2500 KWH will be at £0.08 per KWH or free with solar. The costs of using off-peak electricity and solar to heat hot water results in.similar costs to using gas, but much lower emissions. For hot water, I can see that using electric immersion heater, it uses only about 60% of the KWH equivalent of gas, for similar household usage. Maybe, despite being only 11 years old, our boiler is just highly inefficient.

Given my data science background, I have built regression models with temperature days, actual internal temperature and gas consumption to heat each room. Due to heating individual rooms at a time, it's likely that the boiler is not condensing properly, and getting a big hit on efficiency. For example, to heat the open plan living kitchen dining room, it uses around 15 KWH of gas on a cold day in the morning for an hour, but definitely that much heat is not being put into the room. My hypothesis is that, if we use IR panels in that space, we could boost 2.2 KWH heat using off peak electricity before 6 am and then probably another 2.2 KWH from battery/grid to top up during our morning routine. Assuming that typically you would require to run the panels for 1/3 the time to maintain the room temperature. This would result in similar costs to using 15 KWH of gas, but 1/6 the emissions. From my smart meter readings and Tado charts, I can see that this room alone uses about 25 to 30 KWH of gas on average per day in the heating season. Some days more, some.days less. With this room and the hot water shifted to electricity, the overall emissions should come down significantly. That's the plan.

Having said that, like any experiment, only data can prove the hypothesis. If this doesn't work out as planned, A2A or A2W would be the next step.

Posted by: @chandykris

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Due to heating individual rooms at a time, it's likely that the boiler is not condensing properly, and getting a big hit on efficiency.

I had a fully zoned system and had a major hit in efficiency with a gas boiler, just because short cycled. Dezoned reduced flow temperature etc, reduced short cycling - reduced gas bill by half.

Posted by: @chandykris

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KWH

This is written kWh, not KWH.

Going back to your gas boiler

There is lots you can do to make it efficient and transition to heat pump.

If a system boiler how is it wired up. You need on X or W plan, so it works as priory demand hot water (PDHW). This allows you to run two boiler temperatures high for hot water and low or weather compensation or room compensation for central heating.

Your cylinder can be upgraded to heat pump cylinder. This has a huge 3m² coil and allows the boiler to run cooler or heat up the cylinder really quickly.

Using your example of the kitchen, if you are trying to heat that alone from the gas boiler it will struggle to do it efficiently. Boiler can only turn down so far, typically in 6 to 8kW is the minimum output. For a boiler to run efficiently it needs two things, volume of water and flow rate. Imagine a kettle, it has a output of 3kW. The water volume it holds dictates how long it runs for. A teacup of water, less than a minute, full 3 to 4 minutes.

The same is true if your boiler, with the added complications of

1. It is more powerful 

2. Holds a small volume of water

3. Relies on flow to and from the boiler to keep it happy and not overheat.

(Same is true for boilers and heat pumps)

So if you only have a couple of radiators available, the boiler struggles to get the heat away quickly enough, the return temp is higher than it expects to see, both cause the boiler to go in to self protect mode, it shuts down, waits 10 mins and tries again. Repeat. Each time it has to heat up the boiler, the pipes and radiators, so spends 2 minutes doing that, 30 seconds adding heat to room, then shuts down again. So 2.5 mins of work 30 secs to minute useful work.

Boiler system design should be no different that that designed for a heat pump. But is because gas was historically cheap and poor design hidden as an acceptable cost.

Thanks @johnmo 

If you plan to live in your home for a while so the heat pump will be yours for the foreseeable, and you know how you like to run your home, I think your ideas on zoning are sound. It is considered normal to heat the whole house to a single temperature in one zone. It is also normal to run the heating continuously, this ensures a good COP so you are not asking the HP to do a huge temperature lift at once. A 200m2 house is quite large, so zoning sounds pretty wise.

I agree with the above, get an enthusiastic and knowledgeable installer who you can discuss these things with - you can hopefully filter out the ones that want to do the bare minimum on the phone.

Thanks @energy-optimiser

Just wanted to post an update from the discussion two months ago. After much deliberation I finally decided to continue with the IR experiment.

So far, it's working great. It's not peak winter yet, but the odd cold snap we had recently helped me test the system and compare against our prior year gas consumption based on similar degrees days.

We have installed three IR panels totalling 2.2 kWh in the open plan kitchen living area (0.9 kWh, 0.7 kWh and 0.6 kWh). The 0.6 kWh unit is actually a 1.2 kWh at full capacity, but has a 50% level as well. Also got the 1.2 kWh unit installed in one of the studies and set to run at 50% output level. The 0.9 and 0.7 kWh panels are mounted on the ceiling and the 1.2 kWh units are mounted high on the wall. The kitchen panel at 0.7 kWh and the dining room panel at 0.6 kWh output run for an hour each and the living zone panel of 0.9 kWh runs for about 3 hours. Overall the room is warm, toasty, and feels very comfortable. The panels are set to run at 19 degrees, but keeps ticking over once steady state is reached. So, the living zone panel will heat for about 30 minutes then it's off for 90 minutes.

W are managing to heat the big space with just 1/4 of equivalent gas in kWh we would have consumed otherwise. So, the whole room uses about 3 to 6 kWh in a day. I get the system to run for an hour in the off-peak times to boost the heat, and then as and when we need it. The cost is the same as what we paid for heating with gas and the emissions are 1/5 when compared to heating with gas.

Looking at last year gas consumption and heating activity on Tado, this room consumed about 50% of gas. Not sure why, maybe an oversized radiator, not balanced or the fact that there is a sofa against the radiator. The hot water which consumes about 30% of our gas usage has already been switched over to immersion heater at off-peak times with similar costs and 25% emissions. The upstairs bedrooms and one of the lounges will still run on gas central heating. Overall, we should end up with 40% emissions as heating fully with gas and at similar costs.

Once tested over the full winter season and have more data to analyse, I might switch over to IR for the other lounge and bedrooms next year. But need to figure out how to heat the towel rails in the bathrooms.