@johnmo 

If you compared to a 45 design at -7 you are taking a 20% increase in heating costs, if you are forced to flow at 55.  @ivanopinion

 

The object of the exercise for me is to negotiate my way around the 50º design temp through the back door, so to speak. Despite still seeing other 🐙 customers getting 45º design temps my lot won't (or I suspect, can't) budge.

So..... I've been attempting to negotiate slightly bigger radiators to give me a wee bit more room for manoeuvre after the install is done and dusted - I'm hoping for no more than 40º flow temps, preferably less.

I'm shoe-string productions right now - I can't afford to buy new rads. My install team aren't daft, they know perfectly well what I'm doing and so far have played along. 

But the -1.3 thing is just an expression of my irritation with a) tick boxes of any sort; b) unreal tick boxes that bear no relation to the reality of the location. 🤷🏻‍♀️

Posted by: @Anonymous

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The jump in heat demand from -1.3 to -7 is about 15% so unlikely to make the next sized heat pump a requirement.

I disagree it is unlikely. It all depends. 15% is the difference between 5.8kw and 6.7kw, so maybe a 7kw machine would be OK for both levels of heat loss and a 6kw would be too low for both. But 15% is also the difference between 6.5kw and 7.5kw, so a 7kw machine might be OK for one but for the other you'd need the next size up. Which would be overpowered for the vast majority of the year.

Posted by: @Anonymous

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If you compared to a 45 design at -7 you are taking a 20% increase in heating costs, if you are forced to flow at 55.

For a handful of days per year. 

 

@lucia This technique worked for me; the installers were, as they all seem to be, designing for 50 degrees and I requested and had fitted radiators that provide our very comfortable 22.5 degrees around the whole house and 25/26 degrees in the bathroom at ~35-45 degrees LWT when the temperature is minus 2 or 3 degrees. We are very pleased that I percy veered on this and although our installers were possibly not the best ever team who have worked in our house but at least, they demonstrated a degree of ‘flexibility’ for our installation. I suspect that they would normally treat their average customer as less well informed and remarked to me that they rarely came across customers who knew just what they wanted! Regards, Toodles.

Sounds like Outfox the Octopus. 😊 . Which is my plan when/if they give me a proposal.

@ivanopinion you must of spent ages come up with some vague numbers like that. You didn't even allow for DHW heating

@lucia I got my Octopus contract wohoo! Guess the design temp? yup 50 C. However I am generally pleased at first sight but will be checking  over the weekend to try to see how it would be at 45 C . I think the ground floor is OK but I may upgrade some bedroom rads myself. The odd one is they want to change my recently fitted 600 by 600 K2 with one of a lower output. So I'll either let them do it and keep the one they remove or keep the new one. 

@jancold Yay! Nice! Would you like my referral code? Then we both get £100 off. 😁

They want to change a rad for lower output? No way, that's nuts. 

Posted by: @lucia

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They want to change a rad for lower output? No way, that's nuts. 

Problem best dealt with onsite imho.  The onsite plumber will almost certainly be happy to leave you the new rad and knock off an hour early.

 

@lucia the surveyor did mention the Kraken software glitch which he said he would correct. However there will be two other rads in that room and the difference is small. Still a free rad I can use elsewhere. The referral sounds good but sure where I enter it? I am getting a free service to compensate for the long delay.

@jamespa Agreed and I have made the site for the pump easier for them to install.

Posted by: @jancold

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@lucia the surveyor did mention the Kraken software glitch which he said he would correct. However there will be two other rads in that room and the difference is small. Still a free rad I can use elsewhere. The referral sounds good but sure where I enter it? I am getting a free service to compensate for the long delay.

What Kraken software glitch? 🙈

If you can do your own rad changes there's no worry - me, I've yet to attempt any plumbing at that level, kitchen tap changes are the extent of my expertise. 😁

As for the the referral - you could add it when you sign your contract I guess? They add them to your energy account I believe - so you could use it for the service contract I guess? Or energy bills?  Or maybe it won't work - but here: Octopus referral code: 4593442

My installation starts in a week - give thanks, I'm done with boiling saucepans for hot water and no heat. 🥶

 

@lucia Thanks for the referral I'll put it in my mail to Brad before signing the contract.

Stu , my surveyor said Kraken sometimes replaces radiators with ones of less output which has to be manually corrected, either he forgot or the monster overruled.

Boiling saucepans, no fun! hopefully our boiler will go on till the installation date.