Posted by: @julianc

@mona I’ve just been pressing buttons to on the Daikin. It says it’s consumed 1088kWh of electric and produced 4725kWh of heat. So a COP of 4.34. I don’t believe this number

Hi Julian,

I remember reading in some of the manufacturer's data that they don't claim extreme accuracy for their energy measurement. Electrical energy is fairly easy to measure with reasonable accuracy, the problem is measuring heat energy with anything approaching accuracy, since it involves measuring two individual temperatures and the flowrate of the water.

@derek-m I agree Derek. But the electric consumption on the Daikin screen is below the actual meter installed with the ASHP.

So hey ho. But either way I’m happy so far

Here's @julianc speaking about his heat pump:

@editor 

another award winning performance from @julianc; a true professional as always.  

Seriously though, good interview and well done. 

Haha thank you, thank you. It was a good chat. I don’t hear my Midlands accent until it’s recorded. Damn. And I wish I hadn’t mentioned my Octopus rate. They’ll be on to me to increase it 😊

Hi

I'm new to the forum but been browsing for a week. I've read some great content and great contributions from a number of members, so thought I should join and say thanks.

I had an 11kw Daikin Altherma monobloc fitted in January. It has been a painful experience to be honest but I'm coming out the other side now and the system is mostly working, a 'niggle' of the system switching on/off a lot which I don't think it's supposed to do, but that'll wait for another topic area I think.

Part of the intro you've asked for is:

- floor area, 175m2

- property built, 1964 bungalow but I extended, refurbished and insulated it well in 2014.

- current heating and energy use. 11kw ASHP. Difficult to say as just switched to elec but expecting about 8000kwh

- EPC rating and heat demand. EPC B, heat demand, I think it's about 13-14000kwh but heat loss calculations by the installers estimate 20000 (is this part of my problem?)

- home warm enough? Hasn't been but working towards it and loving the feedback I've already read on here

Hi, very pleased to have found this site after visiting the "My Home Farm" ASHP pages. 

I work in construction & have been interested in green tech for years, meanwhile living with, at different times; forced air electric heating, coal fires, gas fires, night storage heaters, (all of these with electric hot water cylinders) & more recently, gas fired central heating, part solar water heating & underfloor heating.

I only know a bit about it but I'm interested in GSHP to replace night storage heaters in a project that only has an electric supply.  I know a little about ASHP, just about enough to have recently advised a customer not to have it, as they have a low income & a large, mostly uninsulated, Victorian solid walled house that requires a huge amount of work to bring up to scratch. Another acquaintance has a converted farm building with ASHP that seems to be underpowered for the volume of the property, which is also solid walled & has only about 50mm of sprayed insul. foam behind the dry lining. I have been banging on about insulation (or the lack of it) for years!

It seems that undersized ASHPs, relative to the property size, age/type & levels of insulation , might be partly to blame for the problems people have with them.

I'm quite concerned about the Govt desire to have many ASHP installs when a huge number of UK properties seem to me to be inappropriate for the tech (at least without other major refurbs). "Hydrogen ready" gas boilers are now available but there seems to be disagreement as to how ready the rest of the gas system is for them. Added to this is the ability of the electricity infrastructure to cope with potential large increases in electric vehicle charging on top of a bulk changeover to ASHPs as we come off gas CH. 

@flowboy 

Hello and welcome to the forum.  

I agree, an undersized heat pump and a poorly insulated house is likely to be an expensive combination.  There are three things that make a HP less efficient; low outside temperature, high flow temperature and making it work hard (high compressor frequency). If your house has has poor insulation you're going to need high flow temps to heat it.  If you have an undersized HP it is going to be working hard.   Unfortunately you can't do anything about the weather. 

I think there are more houses that would be OK with an ASHP than some people think.  There are some where it would be an uphill struggle though and I think you gave your customer the right advice.  Anyway, we should be making all homes energy efficient, not just ones with ASHPs.  Cheap gas has meant that we haven't bothered up till now.       

@flowboy 

Like you I'm a construction-industry professional - retired but with a long-standing interest in low-energy buildings. I think a lot of people have a mindset developed over years of using high-output gas boilers with programmers set to 'twice daily' warming up their homes quickly in the morning then again when they return from work & school. The power needed to heat a house quickly is far higher than is needed to cope with steady-state heat loss - keeping the house at comfort temperature once it has warmed up. Heat pump power is generally far less than gas boilers and so can only heat houses fairly slowly, but should be fine maintaining a steady temperature. In most older houses brick or stone walls have a high thermal capacity and take a lot of energy to heat up but once warmed up will maintain their temperature well. With more people working from home more these days, keeping houses warm all day makes more sense. In this scenario, always-on heat pump heating systems with thermostatic control should be reasonably efficient even in older homes. Current energy pricing, with gas far cheaper per kWh makes heat pumps seem expensive to run, but shifting the renewable-subsidy costs from electricity to gas, along with rising gas prices will shift the balance.

@flowboy welcome to the forum. I listened to a Betateach pod cast with a technical director from Worcester Bosch boilers. H2 ready means they can burn some H2, but require some upgrade (can’t remember if it was the burner itself) for about £50. 
But because the calorific value of H2 is only 25% of CH4, you can only run at a maximum of 20% H2 in the system. 
Plus you have the massive losses to create the H2 in the first place (up to 70%) and losses from pipes as H2 is such a small molecule. 
So there is a place for H2 in decarbonisation of the economy, but I’m not sure it’s home heating

@julianc I am not sure where you get 70% losses to make hydrogen. The process is very efficient and runs at about 75-80% efficient conversion e.g. 1MW in should make 750/800kW of hydrogen.

The H100 Fife 100% Green Hydrogen project is going to give some really good learnings about whether hydrogen could realistically replace gas in at least some existing homes and businesses (gas heating, fires, hobs, cookers, barbecues) and infrastructure. This is one to follow for those interested. Local offshore wind turbines will be providing the energy for the hydrogen generation. 

Separately the injection of up to 20% hydrogen into the gas grid is currently scheduled to commence in 2023, ramping up over time. It will be interesting to watch how widespread this is and how much is injected. There are already smaller scale projects injecting up to 20% hydrogen into homes. 

I am not convinced either way about 100% hydrogen in the home but interested to see what happens. I can't currently envisage it will be available nationally, and may only be in certain areas of the country.