Green Central Heating Boiler/Hydrogen Boiler/Air Source Heat Pump - which one and how

Catbells

I had a quote from British Gas for a Worcester Greenstar regular CH boiler.  I have a month to make up my mind about whether I buy it from them.  I am assured in writing it is more efficient than my Potterton which is 20 years old and will not last forever and it is anyway inefficient.  The total cost is £3,599.  I would prefer to put this money into a more Green system - Hydrogen (don't know much about them) or an air source heat pump which is too expensive for me unless there is a subsidy from somewhere - Government maybe.  I've looked for grants without luck.  My house is over a hundred years old - I believe ASHeat Pumps need underfloor heating to work properly so that would be a problem throughout my house but could maybe do it downstairs only.  If you have any suggestions I'd welcome them.  I feel I can't be the only person with this dilemma.  

Martyn1981

Hiya. BG and Octopus are offering ASHP installs from ~£3k (after deducting the £5k subsidy).

Might be worth you Googling them and seeing what you think. Obviously those prices will rise fast if your home isn't ideal, or large.

Any replacement boiler should be hydrogen ready now, going forward. But to be honest, I can't see it ever happening. To produce green hydrogen from green leccy, and then taking boiler efficiency into account, will require us needing about 6x as much initial RE leccy generation for space heating v's ASHP.

Catbells

Thanks for that.   Your words sound dispiriting regarding Hydrogen power happening in my lifetime (I'm 68).  The boiler as you say is "hydrogen ready" at least.  Do you know where the £5k subsidies can be found for the ASHPs?  

Reed_Richards

I have an Air Source Heat Pump and radiators; this replaced an oil boiler and radiators.  This works perfectly fine but I had to replace all the radiators with ones that had a larger surface area so I could run the heating with lower water temperatures.

You should be able to get a £5000 government grant towards the cost of your ASHP system: https://www.gov.uk/apply-boiler-upgrade-scheme/what-you-can-get

I agree with @Martyn1981 about the dim prospects for hydrogen as a boiler fuel. 

Screwdriva

Catbells said:
My house is over a hundred years old - I believe ASHeat Pumps need underfloor heating to work properly so that would be a problem throughout my house but could maybe do it downstairs only.  

You've shared how old your home is but not how well insulated it is. Do you have add on loft/ external/ internal/ floor insulation? 
If not, I would steer clear of a heat pump unless you are able to install oversized double panel/ fin radiators. 

Martyn1981 said:

Hiya. BG and Octopus are offering ASHP installs from ~£3k (after deducting the £5k subsidy).

I also received a quote from Octopus. £6K after the government grant for the heat pump + hot water cylinder. Their quotes start for £3K but rise quickly as complexity compounds. 

Catbells said:

 I feel I can't be the only person with this dilemma.  

You are not. We were and ultimately invested in a Viessmann 200-W. I have a thread on the 32% savings in gas consumption we experienced last winter here. Factor in Octopus's gas tracker tariff (we just got it), and the savings are hard to beat. 

If your home was ideally suited to a heat pump, I would have recommended one however, I have a feeling you will save more with the V200 boiler instead. 

Reed_Richards

Screwdriva said:

If not, I would steer clear of a heat pump unless you are able to install oversized double panel/ fin radiators. 

This may be true.  You can make an estimate if you have an idea of the flow and return water temperatures being used by your existing radiators and what type they are (single panel, double panel, single panel with convector, double panel with single convector, double panel with double convector etc).

Screwdriva said:
...ultimately invested in a Viessmann 200-W. I have a thread on the 32% savings in gas consumption we experienced last winter here. If your home was ideally suited to a heat pump, I would have recommended one 

I've read @Screwdriva's thread and as far as I can see his house was ideally suited to a heat pump but he still got a gas boiler.  Part of the way he achieved his 32% saving was by operating the new gas boiler at lower water temperatures than the old one.  To be able to do this he installed underfloor heating downstairs and, if I remember correctly, moved some redundant radiators upstairs so those had a greater surface area.  Running your heating at lower temperatures achieves fuel saving with a gas boiler and even greater savings with a heat pump for the same temperature reduction.  But it only keeps you warm enough if your radiators are large enough to cope.        

Catbells

Interesting reading this.  One thing I keep hearing about is 'lower temperatures, bigger radiators'   Sounds logical but initial outlay to replace radiators with bigger ones might be high and having rooms dominated by radiators might be intrusive to the decor.  
 Screwdriva my house is double glazed aside from one landing window.  The walls aren't double bricked on one side though.  Loft insulated.  The original front door which is lovely to look at but 0% insulated has single glazed panels and I'm planning to have it refurbished with double glazed panels and Stormguard insulation.

Martyn1981

Catbells said:

Interesting reading this.  One thing I keep hearing about is 'lower temperatures, bigger radiators'   Sounds logical but initial outlay to replace radiators with bigger ones might be high and having rooms dominated by radiators might be intrusive to the decor.  
 Screwdriva my house is double glazed aside from one landing window.  The walls aren't double bricked on one side though.  Loft insulated.  The original front door which is lovely to look at but 0% insulated has single glazed panels and I'm planning to have it refurbished with double glazed panels and Stormguard insulation.

Hiya, by bigger radiators, they may not have to be longer. If your current rads are double panel, and double large fins, then if you need more surface area, you will need longer rads. But, as a rough rule, each panel, and fin, adds the same heat output on top. So a single panel rad's output can be doubled with a modern one with a large fin, or quadrupled by double panel and double large fins. If that's possible, then the rad won't really look too big, just thicker, and can connect to the same inlet and outlet pipes, without extending them.

Super long shot, but radiator mounts typically have two slots, so if the older thinner rad is mounted on the outer slot, then mounting a thicker rad on the inner slot, may offset some of the additional size ..... but as I said, long shot.


Regarding H2, sorry to be a party pooper, but to decarbonize some industries that are heavy users of H2, like fertilizer, we need to produce a lot of green H2, asap. Most H2 is currently produced from steam reforming of FF gas. So given the need to focus on that, it could actually be a negative move to shift towards H2 space heating.

Here's a handy diagram to illustrate just how much more green leccy capacity and generation would be needed for H2 v's heatpumps. The diagram uses wind generation just for the purposes of comparison.

Screwdriva

Catbells said:

 Screwdriva my house is double glazed aside from one landing window.  The walls aren't double bricked on one side though.  Loft insulated.  The original front door which is lovely to look at but 0% insulated has single glazed panels and I'm planning to have it refurbished with double glazed panels and Stormguard insulation.

Thanks for sharing. Have you ever had a property heat loss survey done? 

While everything Reed has shared is correct, I will add that, unlike a heat pump, the margin for error with a Viessmann 200-W boiler is far greater. Said another way, it will save you money/ emissions even if it replaces your existing boiler as is with no other modifications. A heat pump will not achieve this. 

On the flip side, the more you insulate and substantially upgrade the emitter surface area (rads), the less the heat pump will cost to run in the long run. If you plan to do this work, get the heat pump and some batteries and you'll save the most money. If not, I'd skip it and get the V200.

arms

Don't rule out an Air 2 Air Heat Pump. Our old Baxi back boiler died last winter and the quotes I was getting for an ASHP with radiators were well out of my range and the amount of disruption to go with them, lifting floorboards, changing radiators etc. Lots of requirements for extra insulation too.

Air 2 Air was a simple install with 3 units downstairs and a ducted unit in loft with vents in each bedroom. much cheaper to install and run, instant heat and similar energy saving to Water ASHP.
The only thing I need to worry about is sorting heating water but we use an electric shower so immersion heating during Go 7.5p kwh is more than enough. 

shinytop

arms said:

Don't rule out an Air 2 Air Heat Pump. Our old Baxi back boiler died last winter and the quotes I was getting for an ASHP with radiators were well out of my range and the amount of disruption to go with them, lifting floorboards, changing radiators etc. Lots of requirements for extra insulation too.

Air 2 Air was a simple install with 3 units downstairs and a ducted unit in loft with vents in each bedroom. much cheaper to install and run, instant heat and similar energy saving to Water ASHP.
The only thing I need to worry about is sorting heating water but we use an electric shower so immersion heating during Go 7.5p kwh is more than enough. 

They are good in places with relatively short, mild winters.  I'm not sure I would want to rely on warm air heating only in our (UK) climate.  That's just my opinion. But we're all going to have to accept some change to reduce emissions so if you're happy that's great. As you say A2A is definitely cheaper to buy.

You do need specific planning permission if you have more than one A2A or if used for cooling.