Thank you for the welcome.  We will need at least two rads. 

@mikefitz, if you go down the Stelrad route, they're really great rads and have been a game changer for us. Are you thinking of getting K3s?

Hi - very useful discussions. It's great to have access to such a lot of helpful advice.

Another couple of questions: 

None of our estimates for installation of ASHP and radiator replacement specify the type of radiator. I guess they think the customer simply isn't interested.

1. We have one estimate that specifies steel radiators. Are the Stelrad radiators steel or aluminium? I couldn't see anything on the website about this.

2. We had one estimate coming in at £16,000. If we wanted to change our radiators they would charge £450 per radiator (all in, including labour). This seems quite steep. What do others think about this pricing?

3. One installer suggested that we change all the radiators downstairs but leave the existing radiators on the first floor alone. We have a one and a half storey house - the bedrooms/rooms upstairs have dormers and velux windows. One of the reasons for this is to reduce the cost but it's also to avoid changing our single pipe system upstairs together with the assumption that all radiators would be on all the time (as they probably would) and, helped by warm air rising from the ground floor, we would be warm enough. What do others think of this proposition to change only half our radiators.

Sorry, that's three questions......

1. Standard Stelrads are steel.  Aluminium will be more expensive. 

2.  Our quote was £16000 for everything including radiators (we had none before).  On the quote it was £3800 for radiators, pipework and installation, for 12 of them.  We needed another 2 in the end and they charged another £450.  K2 Stelrads are in the region of  £100-200 to buy, depending on size. £450 each to replace sounds high considering they will be in the house and flushing the system anyway.

3. Heat will rise from downstairs but the more that does the colder downstairs will be (obviously!).  You could try only changing downstairs and see how it goes.  You probably won't want the bedrooms as warm as the living area.  The amount of heat given off by a radiator depends on the temperature difference between the water in the rad and the target room temp - the delta T. The standard for heating calculation is 50 (e.g. room 20 and radiator 70).  ASHP rads have a delta T of 30(ish) (e.g. room 20 and radiator 50).  To give you an idea that will give you about half the heat output in watts as 50.  Google "delta T correction" for more details. 

@kev-m thank you. I wondered how long ago you received the quote for £16k. It's just that prices for construction, plumbing, heating, electrical work, have increased steeply over the last year.  

Yes, I too thought that £450 per radiator sounded high (despite including labour etc)

Thanks for the advice about Delta T correction. I'll look that up.

@jennyross, the quote was March this year.  

@kev-m who was your installer? 

We are needing to have our underfloor radiator pipe system altered too (even though it's electric wet heating) so I guess we should expect our estimates to be higher. 

@jennyross, it was JL Phillips from Newark, Nottinghamshire.

If you did leave changing radiators until later, any plumber could do it and you shouldn't have to pay any ASHP premium. I'm not an expert but fitting a few rads should be a couple of days work plus the cost of the rads, unless a lot of new pipework is needed.

@jennyross 

Hoping to install later this year but in March was quoted £290 per rad.  I have no rad's or pipework present so a full install inc' plumbing.  Not just swapping rad's.  See full quote attached.

@jennyross fyi @morgan quote is the same supplier as ours.  Ours ended up £300 per rad on the same basis. 

@kev-m Are you still impressed/pleased with your installation and system Kev?

Posted by: @kev-m

@jennyross, it was JL Phillips from Newark, Nottinghamshire.

If you did leave changing radiators until later, any plumber could do it and you shouldn't have to pay any ASHP premium. I'm not an expert but fitting a few rads should be a couple of days work plus the cost of the rads, unless a lot of new pipework is needed.

We had five rads changed in a day - it took the guys about an hour a rad to remove the old one and fit the new one. Would strongly recommend while you have the guys there to balance your radiators, which made a big difference for us – that took a few hours to do in our house.