Pro's and cons of a heat pump

I suspect that once he gets a quote for how much it will cost to get connected to gas, the heat pump may seem like the better option.

Ive just been doing a bit of reading about them. I must say I am not convinced. Especially as it's an older house (1970s) with wooden floors downstairs. They put our gas in for free 25 years ago if we used BG as our supplier for the first month

He is most unlikely, and in that sense he is exactly  like the rest of us, to be still enjoying (relatively) cheap gas in 25 years time.

Whatever heating is chosen, if contemplating the disruption of pipes and radiators being put in, also consider the extra upheaveal but longer term benefits of installing cavity insulation, and under the wooden floor insulation, and generally draft proofing and then ventilating in a controlled way so that the loss of heat is well managed.

Gas may well make economic sense for now, but the trend will be for us to import more and pay more for it relative to electricity  in the longer term,

Generally both heat pumps and condensing boilers when working efficiently need rads that are somewhat oversized compared to traditional practice, as the circulating water temps are lower but again, nothing beats knowing (and being in control of) your actual heat losses, so you know how much heat you really need in each room.

Mike

There even are those that think gas will be gone in  less than 25 years.. https://www.nesta.org.uk/feature/future-signals-2024/shutting-down-the-gas-grid/

I've designed and fitted HP's. I'm an advocate for them. The one in my house is cheaper to run than the gas boiler we had in the previous house. Please note, it is the heating design that determines how good the HP is.

The outdoor units are all much of a muchness, the only real difference is the controls between different Makes. My personal favourites are Daikin, Grant and Nibe. Others will say Vallaint/Bosch etc. There isnt a great deal of diffence between any of them. Spares back up and usage of the controls are bigger factors for the homeowner. My own controls are never touched. They were set up when it was installed, I cannot recall touching them since to adjust anything.

I must stress, it is the heating design that makes or breaks the install. Octopus et al use a flow design temperature of 50 deg C. I would definitely design at 35 deg C. Each 1 deg rise in flow temperature uses 2.5% more energy to get that 1 degree. Hence a HP at 50 degrees uses 37% more energy than one that runs at 35 degreees.

I have been to many HP installs that are really badly designed and fitted. Sadly, Plumbers have been getting away with it for 40 years, in doing little design for their Installs. A gas boiler is usually oversized by a long way. Great, it heats the house up quickly, and will easily heat that house to 30 degrees internally, but, the cost to the homeowner is hidden - they arent aware that they are paying too much as their boiler is quite in-efficient for their use. The same mantra has happened with Heat Pumps, in that they just fit them, and think they will automatically just work. They wont, well, they may, but the running cost will be high. Get it designed properly, and it'll be a really good system.

Yes, you will need bigger radiators. Basically, the lower the flow temperature, the larger the heat emitters have to be. Typical new gas boilers (should) flow at 55 deg. A good HP will flow at 35 deg., so a radiator roughly twice the size will be required. This is all worked out from the house heat loss requirements. If a heat loss survey is done, the 'surveyor' should spend at least a hour in the property, possibly more, to get a good basis for the calculations for each room. Do not employ anyone who does not do a proper heat loss survey - it is the fundamental base to ensure you have a well designed system. Recently software has taken over, and they go round with a phone and record the house layout etc. The software then works out the heat loss. This is coming on, but, IMO, does not give as accurate  a figure as a proper survey. If it's within 10%, thats good, but why would you want to pay 10% more on your bills? Get it done right, and you'll be happy, with a well specified, efficient system.

Follow up if you have any more queries.

If you are putting in central heating for the first time, it seems sensible at least to plan for a heat pump. If you choose gas for now, but have larger radiators than it needs, the rooms will heat up quicker and then the TRVs will close.

Gas may be available now, but is already excluded in new builds. I suspect that new gas connections may also be banned soon, so if you want it, get it while you can.

By far the most important thing is to maximize insulation with particular attention to stopping draughts through windows and doors.

My gas boiler broke down last year and I installed a heat pump to replace it. I don't have a full year's figures yet to compare, but it's looking like it working out somewhat cheaper than the gas - more so when you add in the lack of gas standing charges.

However - I do have underfloor heating throughout and a large thermal store - so the heat pump can run at about 35 degrees for space heating and make the most of off-peak tariffs (I've got one that runs 0500-0900 and 1300-1600). On the domestic hot water side (hot tap water) it's significantly less efficient having to produce at 55 degrees (and due to having loads of thermal insulation DHW is probably a larger proportion than for many). Still it seems to work well.

   - Andy.

Do the heat loss survey, and dampness first. 

Cavity wall insulation, loft insulation, proper window vents, kitchen & bathroom extractors, checking the underfloor solum, air vents, drainage, should be first thing to do.

Gas is a 'heat the room' solution. Heat pumps are 'heat the house'. 

It's not clear if the house already has plumbed water radiators. If not you may want to look at air conditioning (heats & cools) as an alternative to the cost of the plumbing. 

As noted, if the house is cold, look to put on a jumper (and jacket) for the house (insulate, no drafts), rather than trying to warm up by holding a cup of tea and shivering...

We've just had to replace a rotten ground floor room, sort the drains & solum, get cavity insulation and sort leaking roof & insulate. Heating isn't the cure, though nice to have.

alanblaby said:

so a radiator roughly twice the size will be required.

The extra thing to notice/add is that most gas boilers are timed (big heat pulses), while Heat Pumps are 24/7 (smooth & stead) with a small temperature offset overnight. This can allow similar sized radiators (if designed properly!) or reuse of existing radiators. 

Hardest bit is to stop expecting the 'hot bum' effect from leaning on radiators!. 35C feels cool.

I've turned down our LPG boiler's flow temp well below the condensing point (that's 55C mentioned) to a "3" (~45C) and it keeps the house steady & comfy (except when my wife turns all the radiators off because there's no one in the room!). An we are on micro bore piping. 

Chris Pearson said:

stopping draughts through windows and doors

But not total stopping up. Our kitchen had double glazing with no vents or extraction [no cavity wall either], plus 'plaster on the hard' and open cavity. The condensation was horrendous.

Had to install vents on all the hopper windows, an extractor, cavity toppers (and ultimately, cavity wall insulation and air brick liners).

There are lots of little nuances that have effects over the months and years that the desire for instant heat can hide.  [Seal Tight, but Ventilate Right ??]

Philip Oakley said:

The extra thing to notice/add is that most gas boilers are timed (big heat pulses), while Heat Pumps are 24/7 (smooth & stead) with a small temperature offset overnight. This can allow similar sized radiators (if designed properly!) or reuse of existing radiators. 

Unfortunately, that will not work. There is a formula for working out the rad size, and there is no way a same size radiator will work properly at two wildly different flow temperatures.