P
Perfectionist
You have NG? Forget ASHPs. Get yourself a quality condensing boiler with weather compensation. They are cheap to buy and run. No contest here.
ASHP - Wet system
- Thread starter ArgyllMC
- Start date
You have NG? Forget ASHPs. Get yourself a quality condensing boiler with weather compensation. They are cheap to buy and run. No contest here.
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probably is but seeing as the op ain't got gas it's a bit pointlessperfectionist said:
ahh what a giveaway
must be bored with screwfux
P
Perfectionist
probably is but seeing as the op ain't got gas it's a bit pointlessperfectionist said:
ahh what a giveaway
must be bored with screwfux
He said he had a gas system and was using it for another 2 years. I am bored with Screwfix that is why I asked about Tool Station.
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P
Perfectionist
oh. I need to read back.
You clearly have not bothered to read this thread to understand the OP's situation. He clearly explained that he has no NG.
If you have come from Screwfix then that might help to explain it. However, on this forum most of the genuine replies are from industry professionals who do try to read and understand whats involved before they reply.
P
Perfectionist
I know now. But Oil is still the better option with the ASHPs on offer, the Sanyo excepted until proven of course.
What is this fixation about Screwfix? On another thread I have done a Tool Station comparison.
As to professional expertise, at least one on this thread questioned yours.
Efficiency is defined as output ÷ input.
A radiator is designed to give out heat. So the efficiency of a rad can be calculated from heat out ÷ heat in.
If the return water is the same as the flow temperature, then no heat has been put into the rad and no heat can be given out, so the efficiency is still 100%.
As the heat input to the radiator is always the same as the heat given out, the efficiency must always be 100%.
This is veering off topic and we’ll have to agree to differ.
Wilst you can agree to differ, I do have to say that I agree with D Hailsham's defination.
I now wonder what your defination of boiler efficiency is ?
Flow temperature
______________ = Efficiency % ???
Return temperature
I now wonder what your defination of boiler efficiency is ?
Flow temperature
______________ = Efficiency % ???
Return temperature
Uh-oh, I sense trouble brewing.
You’ll have noticed I hope that I don’t disagree with the definition of efficiency, just the proposition that a radiator is a 100% efficient.
For a boiler, or any heat engine, I think I’d express it as the conversion of the potential heat energy contained in the fuel put into the heat generator (boiler) and the amount of heat energy taken out in the medium it is designed to transfer it to (in this the circulating instance water).
Potential heat energy lost through imperfect combustion, heat energy leaving in the combustion products and loses through the appliance casing I would classify as contributing to the appliance inefficiency.
This isn’t getting involved in seasonal efficiencies etc or including latent heat released which at one time was added by certain manufacturers to their advertised boiler performance figures giving a potential maximum efficiency of 108% if I recall.
With regard to the radiator question; a mass flow rate of water passing through a radiator at a given temperature has a specific heat capacity of X. If the water leaving the radiator has a temperature higher than that of the air in the room in which the radiator is sited then the radiator has not transferred the entire SHC to the medium it is attempting to heat (the air) by conduction, convection and radiation.
If you treat the radiator as a heat emitter then any heat that leaves the emitter and is not transferred to the air is an inefficiency. The quantity of inefficiency is actually designed into the radiator by the engineer when he or she determines the design flow and return temperatures. That they help with maintaining suitable flow and return temps across the system for the benefit of the overall efficiency is a given but that’s not what we’re talking about. It’s exactly the same as maintaining conditions in a conventional boiler to ensure condensation does not take place in the exchanger, flue hood or flue – a design inefficiency.
D_Hailsham wrote
Efficiency is defined as output ÷ input.
No problem with that
A radiator is designed to give out heat. So the efficiency of a rad can be calculated from heat out ÷ heat in.
No problem with that
If the return water is the same as the flow temperature, then no heat has been put into the rad and no heat can be given out, so the efficiency is still 100%.
Not sure why this is mentioned, I didn’t refer to it.
As the heat input to the radiator is always the same as the heat given out, the efficiency must always be 100%.
This is the bit that cannot be so unless the return temp is the same as the air temp in the room because the radiator has transferred all the heat it received to the surrounding air.
I tried to agree to differ and look what it got me!
if the great god agile says it's right who are us mere mortals to argue
now behave yourself or you will be beaten with a wet woodbine till you beg for mercy
now behave yourself or you will be beaten with a wet woodbine till you beg for mercy
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Of course the customer cares about all the costs its just not explained to him thet they make up probably 85% of the fuel cost.
As for the ATAG,its absolutely no more efficient than any other boiler during CH demand,what it is however is more efficient during hot water production.As the hot water production is probably a 1/4 of a combi boiler running period is that such a great saving when it only increases its efficiency by 5-10%.
As good as it is its still not 100% efficient.
Having to fit a Zenex to an existing band A boiler is a waste of money,last time i looked the zenex was £700ish quid
Lets look at the alternatives,solar waste of money waste of time,free hot water at a ridiculous cost during the high sun periods,no CH effect during winter when its needed and little effect on DHW.60% saving max on DHW production.
GSHP under water, seen plenty done wrong(frozen lake in summer) and some done right,but not many folks have a lake in the garden.
GSHP slinkies,wouldnt install one,seen to many that have failed through excess heat extraction even when laid at the manufacturers requirements.Lay flat is better but requires more room,gshp is 25M2 per KW.
GSHP boreholes,expensive.....no need to elaberate.Look at Nebe,Ice energy,Danfos.
ASHP,weve said enough already. High efficiency 3-400%,but are limited by the refridgerent.Mitsi,daikin,Sanyo all worth a shout,ignore boiler manufacturers units,most cant build gas boilers that well let alone something that A?C companies have been doing for years.
Biomas,expensive to install,needs user maintenance frequently,planning issues for pellet stores,still specialist and not that small scale domestically friendly.Been in talks with Baxi tech about theres,until someone offers a complete pack for the domestic end user they'll be rare as rocking horse poo.
waste oil/veg oil burners,decent bits of lit,if you can get the oil theyre worth considering as an alternative,same setup..tank etc as normal oil.See Kroll for decent kit,but dont be put off by the price.
CHP,limited by manufacturer,still gas driven but produces elec,sell back or utilise its up to the user.the proposed feed in tariff changes might see it become domestically viable.Products at present Baxi ecogen,Whispergen,EC power.
Installation costs will always favour NG boilers if you have NG,but running costs of renewables will save in the long run,it just depends how long you intend to stay.
Having actually compared costs on site between various systems in comparison to a 100%eff gas boiler,i know which way id lean.Most easily accesable products ASHP/GSHP/CHP have caught the differnece between installation and running up within 5-8(dependent upon product),after that your saving so if you have a 10-15 year plan......
Lee
There was an Irish fellow who gave all the costs of running his wood pellet boiler and it was quite reasonable.
The waste oil market is sold out because of the advantage of illegally running vehicles on it. Every chip shop has a buyer for its waste oil.
Both those fuel supplies rely on ready and cheap supplies of waste products. There is only a very limited supply of waste oil and thats already fully used. Pretty much the same for wood as well.
I eye up all those pallets lying around and wonder if I should install my boxwood stove for the winter. But the reality is I would need about three pallets, 15 min to cut them up and time loading and lighting the stove when I can just turn on the gas heating at a button.
Tony
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