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 1 
 on: Today at 01:18:21 AM 
Started by Barrie - Last post by phoooby
ENV200 is a superb vehicle. We have had a 24kw version for the past year and have done 15 k mile in it over that time. It had only done 16 k miles in its first 3 years before we owned it so we are making better use than the first owner. I hope the LEVC eventually goes 100% electric or they increase the electric range incrementally over time. Not been in one yet as I am a cheapskate and use the tube in London but the more Ev's the merrier as far as I am concerned.

 2 
 on: Today at 12:42:01 AM 
Started by stannn - Last post by RIT

It does create an interesting dilemna - how do you (fairly) tax private transport. Right now, its mostly fuel duty. How could you tax electricity at 2 rates - one fo your car, one for the home? Probably not realistically possible

So, anyone got any thoughts? It will happen, eventually.

The tech exists for real-time tracking for cars, so the most likely is going to be a charge for the journey distance and the time of day. It's a vote loser at the polls, but the UK government will need to cover a rather large tax hole over the next 15 odd years. This also provides the government with vast amounts of real-time data, something that many departments would love to have access to (for better or worst).

 3 
 on: October 23, 2019, 11:33:30 PM 
Started by stannn - Last post by A.L.
hello,


It does create an interesting dilemna - how do you (fairly) tax private transport. Right now, its mostly fuel duty. How could you tax electricity at 2 rates - one fo your car, one for the home? Probably not realistically possible

So, anyone got any thoughts? It will happen, eventually.

Why differentiate? Call it a 'climate change tax'  surrender

 4 
 on: October 23, 2019, 10:45:44 PM 
Started by stannn - Last post by dimengineer
Until the goverment taxes things so that people don't notice it should be getting cheaper - afterall as EVs are adopted they need a new source of revenue.  banghead

Well, yes. Tax is inevitable - Death and Taxes, can't avoid them.
It does create an interesting dilemna - how do you (fairly) tax private transport. Right now, its mostly fuel duty. How could you tax electricity at 2 rates - one fo your car, one for the home? Probably not realistically possible

So, anyone got any thoughts? It will happen, eventually.

 5 
 on: October 23, 2019, 10:08:26 PM 
Started by stannn - Last post by RIT
Any sign of weakness in energy costs just gives the local/regional/state government the change to add a few extra 'social obligations' or service fees to the cost depending on how the local market is structured. The UK is a great example, while we have just 5% VAT on electricity (which can be reclaimed by VAT registered businesses) about 20% of the total cost is for 'social obligations' that all customers must pay.

 6 
 on: October 23, 2019, 08:35:40 PM 
Started by geoheated - Last post by marshman
When you are measuring the power input are you recording the actual output water temperature or just what the cut off is set to? Also as Nowty said have you checked flow rates and temperature difference between flow and return on the brine side?

This document illustrates the quite dramatic effect input and output temperatures have on the COP.

When I had mine installed I was told you need a flow rate of around 3 litres/min per 1 kW heat output. My system (10kW) has four loops flowing 8 litres/min so actually 3.2 litres/min.  Also was told to ensure temperature difference flow to return was around 3 deg C.

This Kensa document is quite good:

https://www.kensaheatpumps.com/the-unbendable-rules-of-ground-arrays/

Note also the comment on the power taken by the ground loop pump.  As Nowty says the viscosity of the fluid also makes a big difference - is the antifreeze mix correct, too much antifreeze will make the liquid too viscous for efficient circulation.

In terms of a non modulated compressor cycling on and off and maintaining 35 deg for the  UFH.  It has been mentioned on here before that if you have a heatpump it is far more efficient to run it for longer periods at lower temperatures than to run it like a Gas or oil boiler where it is heating for a few hours in the morning and late afternoon/early evening.  My system actually runs 24/7 during the heating season.  The heatpump will come on and heat the UFH water including the small buffer tank  upto target temp then switch off for a variable period of time. The water then slowly cools down before the next heatpump heating cycle. What I have observed is that the controller aims for a long term average temperature. In my case it seems to be in the low to mid 20's. As this is circulating 24/7 it essentially just balances the heat loss from the house. When it is really cold (really cold for here is only -2 or -3 deg),  the pump will fire up for at most 20mins once an hour, never seen it do more than that. More typically it is on for 10 to 15 mins every 1.5 to 2 hours.  So it is the average you are looking at and not the instantaneous UFH temperature.  If I feel the flow pipe to the UFH, unless the heatpump has just switched off, you can hardly feel it is warm yet the house stays a nice stable 20 deg C in the living areas, bedrooms are a bit cooler, and it never varies.

As others have said I doubt you are going to get a real world COP of much more than 3, less if you are regularly using it for DHW as well.

Is your actual electricity bill a lot higher than you think it should be?  I can monitor the instantaneous power consumption of my pump and at certain times - near the end of a DHW cycle - and the input power can be over 4kW for a short time. If your bills arn't excessive and all your flow rates and temps are correct I wouldn't worry too much.

Roger

 7 
 on: October 23, 2019, 08:33:36 PM 
Started by stannn - Last post by Countrypaul
Until the goverment taxes things so that people don't notice it should be getting cheaper - afterall as EVs are adopted they need a new source of revenue.  banghead

 8 
 on: October 23, 2019, 08:27:57 PM 
Started by stannn - Last post by stannn
........and now, the movie Shocked
https://cleantechnica.com/2019/10/23/first-turbine-for-windfloat-atlantic-offshore-wind-project-moved-into-position/

 9 
 on: October 23, 2019, 07:03:43 PM 
Started by geoheated - Last post by nowty
What i am surprised is that at specific quoted temperatures, the electric consumption is greater than advertised. This is not excusable.

The water pumps will be included as they come off the single supply to the heat pump and are build into it.

But they are also quoted at specific design water flow rates which may be unachievable and you have not mentioned whether you have measured the flow rates or not. If your flow rates are lower than the design rates, then you will get a larger difference between your water flow temp and the compressor gas temp so the gas temp will be higher and therefore won't be as efficient as the datasheet values.

Just because the water pumps are built in does not necessarily mean they are included in the datasheet figures. I mean the pump power consumption of them will depend on the viscosity of the fluid (different antifreeze concentrations) and the resistance of your pipework.

 10 
 on: October 23, 2019, 06:45:50 PM 
Started by geoheated - Last post by geoheated
Ah yes, i fell into that trap earlier on in this thread.

We think its the inductive load power factor. Typically 0.8.
Brings it much closer to the 2.1kW on the same data sheet.

I am logging true power from a meter now so i will log that against the heat output with a Kamstrup and see what the true COP is.

At the same temperatures on their data sheet there should be very little variation. But early indications are far from that.

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