Octopus Heat Pumps

mickyduck55

Hi @EricMears "filling WC cisterns from a cold water tank in loft was the norm" how was the tank filled?

shinytop

mickyduck55 said:

Hi @EricMears "filling WC cisterns from a cold water tank in loft was the norm" how was the tank filled?

Mains water.  The norm was not just the WC filling from a tank, it was that the only mains cold tap was in the kitchen, the others (and the cistern) came from the tank. 

mickyduck55

shinytop said:

mickyduck55 said:

Hi @EricMears "filling WC cisterns from a cold water tank in loft was the norm" how was the tank filled?

Mains water.  The norm was not just the WC filling from a tank, it was that the only mains cold tap was in the kitchen, the others (and the cistern) came from the tank. 

Thats what I thought... and in my home its almost the same today, downstairs loo fed directly from mains rest from tank in loft

EricMears

As is often the case,  this thread has gone off at a tangent !  Refer to post #225 where the idea of pumping rainwater to a loft tank & thence to WCs was floated - principally to save money on water rates.  I endorsed that concept but remarked that there are also other benefits in feeding WCs thus. 

silverwhistle

I save water by yellow/mellowing when family etc. aren't visiting and sometimes jugging dirty bath water direct to the cistern which is only an arm's length away. Low tech but it works! The local stream is rather stressed and I'd like to help in a microcosmic way.

michaels

OK - got a sales call from Octopus Heat Pumps today because I had previously expressed an interest.  Said a full heat pump install to replace my 20kw modulating gas boiler would be £4.4k after the 7.5k grant and this would include any rads that needed upgrading (I suspect at least 6, there are also some vertical ones that I'm sure wouldn't be included) plus a hot water tank (I would actually rather keep my own pressurised indirect cylinder if at all possible as it is in the loft and would be hard/impossible to get the Octopus one there) 

However I would need to pay a refundable £500 deposit to have an actual survey - apparently they are capacity constrained and only want to spend time surveying serious customers.

Now we probably need a new boiler as although ours is highly efficient and only 11/12 years old it hasn't been working great for the last 2 years.  Currently we have added in parallel in the heating circuit an old (12 year old and cheap originally) heat pump I was gifted by my parents, it draws about 2kw but I have no idea of the output, subjectively doesn't feel to be as much as 4-6kw (assuming a cop of 2-3).  Might be worth getting someone in to service/regas but not sure anyone would as it is fairly heath robinson unit/install.  I also have the advantage of V2H so am currently trying to use as high a proportion of 8p night rate leccy as possible but this is limited to the battery capacity and charge rate which means only about 22kwh per day for all electrical usage during the 19 hours of day rate (or less if we use the car).  Upgrading to a bigger battery leaf would potentially increase this up to about 35kwh if we went to a 7 hour night tariff such as the Eon one or an E7 tariff.  Given these options it should be much cheaper to run a modern efficient heat pump than the gas boiler but I feel a spreadsheet coming on....

Exiled_Tyke

Ooooh I'm getting spreadsheet lust!  

But more seriously. they quoted me £5800 after the grant on the same terms.  I don't really like the idea of some kind of all-in cost which must surely have a generous buffer if a lot needs changing. I was also hoping they'd be suggesting one of their own ASHPs with up to the minute technology, but they are not.  I really want to go down the ASHP route and ditch gas altogether but I've dropped the idea for now.  

Reed_Richards

michaels said:

.... plus a hot water tank (I would actually rather keep my own pressurised indirect cylinder if at all possible as it is in the loft and would be hard/impossible to get the Octopus one there) 

The cylinders used by heat pumps have a longer coil with a larger surface area.  The problem with a conventional cylinder is that it takes too long to raise the tank temperature and time spent trying to heat the hot water tank is time not spent heating your house.  I wonder if you could get around this by having a smallish cylinder in series with your existing one, have the water from the heat pump pass through this first then through your existing cylinder whilst using your existing cylinder as the cold fill for the new small one?  That way you get tepid water topping up your new cylinder instead of cold water direct from the rising main.  This might work (or it might not) but it's probably too radical for Octopus to contemplate.  

michaels

Reed_Richards said:

michaels said:

.... plus a hot water tank (I would actually rather keep my own pressurised indirect cylinder if at all possible as it is in the loft and would be hard/impossible to get the Octopus one there) 

The cylinders used by heat pumps have a longer coil with a larger surface area.  The problem with a conventional cylinder is that it takes too long to raise the tank temperature and time spent trying to heat the hot water tank is time not spent heating your house.  I wonder if you could get around this by having a smallish cylinder in series with your existing one, have the water from the heat pump pass through this first then through your existing cylinder whilst using your existing cylinder as the cold fill for the new small one?  That way you get tepid water topping up your new cylinder instead of cold water direct from the rising main.  This might work (or it might not) but it's probably too radical for Octopus to contemplate.  

Yes, I was able to find my tank coil size and heat transfer rate on the supplier website but don't know what the spec required is for a heat pump

shinytop

Exiled_Tyke said:

Ooooh I'm getting spreadsheet lust!  

But more seriously. they quoted me £5800 after the grant on the same terms.  I don't really like the idea of some kind of all-in cost which must surely have a generous buffer if a lot needs changing. I was also hoping they'd be suggesting one of their own ASHPs with up to the minute technology, but they are not.  I really want to go down the ASHP route and ditch gas altogether but I've dropped the idea for now.  

There is a lot of discussion about Octopus prices on the dedicated ASHP groups and the consensus (including from suppliers) is that they are probably losing money on most installs.  It's therefore probably a bargain at the moment. Most reports I've seen reckon the installations are high quality. 

They use Daikin for now, which are decent but not the very latest tech.  Small versions of their own new models should start appearing soon.