I’m not familiar with these companies, but if you’d like me to confuse you further, I can connect you with a highly reputable installer in your area to get another quote. Please let me know.

@eliuccio 

I have a 5kW Samsung and am very happy with it. Vaillant have a good reputation too. 

It would be useful to have some more details on the quotes such as radiator upgrades, anticipated flow temperature etc to try and compare what they are offering. 

The heat pump is the least important part of the system its everything else that makes the difference to efficient running and comfort, so focus on that not what heat pump manufacturer you are being offered. 

You should be hearing terms like open loop from a decent installer and not things like buffer tank or zoning.

Im with @gary. System matters much more than heat pump.  The only addition I would make to that comment is that Samsung controls are a little basic, Vaillant are much better (everything you could really want), I cant comment on Baxi.

Reject anyone who is proposing a buffer tank (other than a 2 port volumiser), low loss header or heat exchanger between pump and heating system

Reject anyone who wants to sell you third party controls (other than Homely for the Samsung or possibly the Baxi).  You absolutely dont need any third party controls for the Vaillant; if you are offered Homely with Samsung thats a good combo to deal with Samsungs otherwise slightly basic controls.  By third party controls (to be rejected) I include a thermostat, particularly a 'smart' thermostat.

Heat pumps work well if connected directly to the emitters and operated with no external controls and either no TRVs or almost all TRVs left permanently fully open.  Heat pumps can work badly if you violate these simple rules. 

Ideally go for someone designing for a flow temp of 45C (or less).  If they arent ask them why not unless its obvious that larger radiators wont fit.

Thanks everyone. This is very useful and reassuring (confirmed my understanding that the pump itself is less important of the design - which would put Heat Geek higher in the list).

Likewise, Sustain set a 45C flow temp but the whole design seems better optimise by SmartHeating with a realistic 47C. Perhaps lower temperature would be possible If I accepted to have bulkier radiators or change more of them (thus raising the price furtther).

Based on the comments I will probably be better off deciding between these two companies (I will wait for the updated quote from Sustain).

I feel I do not need more quotes @Mars but I am attaching these two if you want to have a mopre detailed look at it.

Your time and expertise is very much appreciated! 🙂 

I would look at it as £9.5K vs £11.5K or £15.5K instead of £2K vs £4K or £8K after excluding the BUS grant. Psychologically, that feels easier to compare and justify than 4X the amount between the cheapest and most expensive quote. Then the difference can be justified if they upgrade more radiators to run at lower flow temperature.

We had the same conundrum when we were deciding between two options. We went for the option that looks like 80% more expensive if we exclude the BUS grant. But the difference was around £2.5K and justified by the number of radiator changes. And glad we went down that route as in Feb when it was very cold, we ended up with a very good CoP and cheaper than heating with a gas boiler using the heat pump on the Octopus cosy tariff.

You didnt post the cheapest (21 degrees) quote.  It would be interesting to see that also.

Sustain are proposing lower FT and changing one/two more rads (generally a good thing).  I would want to check they dont intend putting in a buffer tank though.  Rads are as cheap as chips and rad swaps are pretty quick too (I can do 2-2.5 per day and I'm not a plumber!), the marginal cost vs running cost savings will generally argue for lowest flow temp even if it means more rad swaps!

Thanks @chandykris and @jamespa I am attaching 23dregrees quote too. Would then be better to have the quote from SmartHeating redone for a 45C system?

Posted by: @eliuccio

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 Would then be better to have the quote from SmartHeating redone for a 45C system?

If they are prepared to do so yes, then you are comparing like with like.

I just skipped very quickly through the Baxi manual, not impressed with the controller, no better than the Samsung. Vaillant definitely much superior in this department.  That said for the price difference 12Degrees vs the HeatGeek backed quote you can get a Homely with the Samsung.  Suggest to await the Sustain Vaillant quote also.

Looks like 21Deg are quoting for 50C FT, why not ask them to requote for 45C FT.  You could possibly also ask them if they would fit a Homely with the Samsung or for a Vaillant to give improved control options.  I note 21Deg are running pipes up outside wall to loft and basically I suspect bunging a pre-plumbed cylinder in loft.  I wonder where they intend putting the controller (loft no good, but its been done!)- something to ask if you get to the point where they are a serious candidate.

It would be worth understanding the other offers as regards pipe routing, it may be clear from the proposal or may not.

Its worth looking at these details as you get colser.

Looks like 21Deg are quoting for 50C FT, why not ask them to requote for 45C FT.  You could possibly also ask them if they would fit a Homely with the Samsung or for a Vaillant to give improved control options.  I note 21Deg are running pipes up outside wall to loft and basically I suspect bunging a pre-plumbed cylinder in loft.  I wonder where they intend putting the controller (loft no good, but its been done!)- something to ask if you get to the point where they are a serious candidate.

It would be worth understanding the other offers as regards pipe routing, it may be clear from the proposal or may not.

Its worth looking at these details as you get closer.