Upgrading heating system / energy - best option

MBKent21

I am moving to a new property soon and the gas combi boiler will need to be changed at some point as it is reasonably old. I am looking to reduce energy costs as well as carbon footprint. I will be having loft insulation upgraded and will check the cavity wall insulation and get it installed or upgraded if needed. I may well have to change the windows in the medium term which I will look at doing with the most energy efficient ones I can.

My question is, given that I don’t have endless supplies of money, what would be the best option in terms of saving money for energy costs and long term use:

-             Replacing boiler with a more energy efficient hydrogen ready combi boiler (I don’t like having a water tank as I have had them in the past and find them really inconvenient)

-             Replacing the boiler with a micro CHP boiler

-             Installing solar panels

I would not consider a heat exchange / air source heat pump as I rented a property for about 6 months with one of these and it was constantly cold and cost me £95per week to run (my bills immediately before this were not usually over £80 per month for gas and electric).

I want a system that will generate as much heat as needed (I don’t use huge amounts but I don’t like being cold). My bills are currently about £120pcm for gas and electricity.

Also if I went for Micro CHP would it be worth adding in solar panels at a later date when I can afford to, in order to reduce energy costs even more?

Lastly, are there any independent companies / advisors that could come and survey the property to give the best advice without having the bias of trying to sell me something?

Many thanks 

MBKent21

I just found the name of the system I had when I rented - Nibe F370 all-in-one exhaust air heat pump. This is what was costing me £95pw to have a tepid property and lukewarm water when running at full capacity in a 2 bedroom flat. An engineer came out and wasnt able to find any faults or get it working any more efficiently. 

Reed_Richards

Not all heat pumps are bad; I have one and it keeps my property perfectly warm.  Some early installations just did not work properly and I have a neighbour who had a horror story like yours.  In your case I imagine they did not replace the radiators and set the heat pump to provide water at such a high temperature that it could neither run efficiently nor keep the water in the radiators as hot as it needed to be.  Installing a heat pump is far and away the greenest thing you could do because, working properly, it should use about a third as much fuel to heat your house as any other heating method.

That said, at current prices a gas boiler is still much cheaper to run than a heat pump.

1. I think "hydrogen ready" is a pure gimmick.  I don't believe our gas pipelines are up to carrying hydrogen so unless you have a rack of hydrogen cylinders outside your house it won't happen during the lifetime of your next boiler, if ever.
2. My house used to have a combi boiler and it was dreadful.  It was at one end of the house and replaced a hot water cylinder in the middle.  This made all the pipe runs way too long and you had to wait an age to get any hot water.  Also, unless you used the hot taps frequently you would waste a lot of heat trapped in the pipes. 
3. MicroCHP is liable to give you electricity you don't need because you are heating your house with gas.  Unless it will cope with a power cut and you are expecting those to be longer and more frequent in future I don't see the benefit.
4.  Solar panels will give you a lot of electricity in the middle of the day in summer.  You could use this to charge your electric car if it is at home in the middle of the day and you could have used it to heat the hot water in your cylinder if only you had not opted for that combi boiler.  Or, as with your CHP boiler, you can sell your spare electricity to the grid for next to nothing compared to what you pay for it in the evening.

I think insulating your house is far and away the most energy efficient and money saving thing you can do.
  

QrizB

The question really is, do you want to save as much money as you can, or are you happy to spend a bit more to be greener?

There's currently no mainstream heating system that's cheaper to run than a condensing boiler (whether combi or system) on mains gas, and that's likely to be the case for the immediate future.

MBKent21 said:

I just found the name of the system I had when I rented - Nibe F370 all-in-one exhaust air heat pump. This is what was costing me £95pw to have a tepid property and lukewarm water when running at full capacity in a 2 bedroom flat. An engineer came out and wasnt able to find any faults or get it working any more efficiently. 

Those Nibe heat pumps were a disaster, totally unsuitable for most of the properties they were fitted to.

https://www.bbc.co.uk/news/business-19511637

In the system's user guide, Swedish manufacturers NIBE say it is designed to run 24 hours a day which is "the most efficient and cost effective way to heat a home".

But independent heating engineer Geoff Morgan, who surveyed the system, believes the main pump is not big enough to heat most UK homes, which are often not as well insulated as homes in Sweden.

The system can switch to a back-up electric immersion heater when it needs to, but this leads to much higher bills.

"When these are used in Sweden the heat losses of the houses are much, much less. The heat pump does a much bigger job and the immersion heater does a very small amount of topping up," said Mr Morgan.

Micro CHP sounds an interesting idea but as far as I can tell there aren't any on the market at the moment (the one that was marketed was discontinued quite some time ago).

Payback on solar PV could be as long as 20 years, and is unlikely to be less than 10.

tacpot12

I would agree with everything that Reed_Richards has said. The conclusion is that the most efficient way to heat your house and get hot water for you is going to be a modern combi boiler (with heating controls that suit your lifestyle) and to insulate the cavity walls.

A microCHP system won't produce enough benefit to outweight the higher initial cost. 

Without a hot water tank, solar panels will need a battery to provide power when you actually need it, and the cost of the panels + battery won't produce enough benefit to outweight the higher initial cost.

Unless the windows in your property are especially large, you don't need to consider triple glazing. A good double glazing system will give you 90% of the benefit for 80% of the cost. 

You should look into insulating under your floors if this has not already been done. 

arty688

This basically sums up the issues with the current government policy of heat pumps, they don't really work very well without a tank and for the last 20/30 years people have been ripping out there tanks. The only solution that I think will come onto the market if its not there already is a ASHP and tank sited outside which maybe a possible solution of most with a garden.

So like people say first thing to do is insulate if you have to change your boiler gas is still the best option for you without hassle.

Reed_Richards

arty688 said:

This basically sums up the issues with the current government policy of heat pumps, they don't really work very well without a tank and for the last 20/30 years people have been ripping out there tanks. 

My tank had been ripped out but the airing cupboard where it had been was still there so there was no problem putting one back.  If there are issues it's more likely to be with newer houses built around combi boilers and with no room for a tank.

My old combi oil boiler had a small reservoir tank of hot water so it could supply "instant" hot water.  And my heat pump has a buffer tank kept at around room temperature.  Maybe a "combi" heat pump is possible if somebody bothered to engineer one? 

matelodave

Cant see a combi heatpump being a viable solution. A heat pump works best when it's idling away gently rather than flogging it's heart out for a few minutes and short cycling like a combi boiler does when providing hot water. TBH a gas combi is't ever so efficient when it's supply hot water

If you want enough water at a reasonable flow rate most combis are rated at around 25-30kw when heating hot water and modulate down to a much lower level when supplying heating.

Unless you go for a three-phase supply most heatpumps are limited to around 14kw which would be insufficient to provide a decent flow of hot water to fill a bath etc.

As said above the NIBE exhaust air heatpumps were usually supplied by housing association or councils, were usually underpowered and most people didn't know how to use them properly.

Correctly sized and in the right sort of premises they would probably have been OK but a lot of them appeared to have supplied as job lots to councils/HA's who wanted to get the grants or RHI. That doesn't make them bad as such but they did get a poor reputation because they weren't suitable for the purpose that they were being used.

I'm an advocate for heatpumps - I had one for eleven years but there's no way I'd consider replacing a mains gas boiler with one untill there's parity between gas and leccy prices. Energy efficiency usually doesnt equate with saving money unless you spend it on insulation. Even replacing an inefficient gas boiler with a shiny new one is liable to take 8-10years before it sees a payback in reduce eenrgy costs

Reed_Richards

matelodave said:

Cant see a combi heatpump being a viable solution. A heat pump works best when it's idling away gently rather than flogging it's heart out for a few minutes and short cycling like a combi boiler does when providing hot water. TBH a gas combi is't ever so efficient when it's supply hot water

If you want enough water at a reasonable flow rate most combis are rated at around 25-30kw when heating hot water and modulate down to a much lower level when supplying heating.

That's all true.  On the other hand there are 28 mm pipes between my heat pump and my hot water cylinder which implies a fair flow rate.  And when heating the cylinder to 50 C the outlet water temperature works its way up to a few degrees hotter.  And 50 C is actually hotter than I want the water coming out of the tap.   You could also boost the hot water temperature with an instantaneous water heater as required.  Certainly this would be less efficient than a heat pump coupled with a cylinder (except that you have eliminated the cylinder storage losses).  I was just thinking that if there is a market for a "combi" heat pump then it ought to be technically feasible.    

   

matelodave

not wanting to get into a philosophical argument but the return flow into the heat pump after passing through the tank is only around 5-10 degrees lower than the output (unless the tank is stone cold and then it takes a fair time to reheat the tank). You wont get 50+ degrees of hot water from an input of 10 dgrees or so with the sort of flow rates that a heatpump demands.

 A combi has to heat water from say 10 degrees up to whatever the flow temp you need almost instantly and generally the only way it does it is by reducing the flow rate through the heat exchanger - thats why instantaneous water heaters are OK for sinks but not really much good for baths and come the winter even a 10kw electric shower can be pretty pathetic.

MBKent21

Thanks for all the advice. I'll focus on insulating the property to begin with and will look at the high efficiency gas combi boilers. The floors are all wood and I can't imagine they're insulated so I'll look at doing this as and when they need replacing (or if they're click lock with no glue I'll do it as each room is decorated).

One last question. The current boiler is in the loft. Apart from the inconvenience of not having easy access are there any other downsides to this? eg does it cost more to run due to the loft being colder etc? Would it be worth the additional cost of moving it to the kitchen (which I think is pretty much right below)?