CH pump efficiency & savings

[YAPH]

Saw an article in a trade rag about how much you could save by installing a new all-singing CH pump. So I thought I'd check the figures ...

[therustyone]

the motor heats the water a bit so saving on the gas bill, though gas is around 1/3 the cost per kWh.

Rusty

[Andrew Gabriel]

The other thing is that none of the pump energy is wasted - it just goes into heating the water (pumps are cooled by the circulating water). So if you want to argue about savings, the energy cost is not the raw electricity cost, but is the difference in cost between the heating fuel and electricity.

[YAPH]

Yes, I could have factored that in, and also looked at payback time, but I was trying to keeping it simple and first-order.

[John Williamson]

"A new electronic circulator does not put power into the motor to rotate the shaft"

How does that work, then? Hand power?

[Dave Plowman (News)]

It will almost certainly quote figures for a conventional pump working flat out while 'there' one will be on the lowest setting. Then add in the highest electricity tarrif/price to be found anywhere.

[Robin]

I don't argue with your assumptions. But ISTR hearing (on Radio 4?) that many more heating systems in the rest of the EU (or at least the Northern States) are, compared with the UK, run at lower "background heating" outputs for many more hours per day and more days per year. I wonder if that's what's assumed in the sums from the pump makers - ie pumps running ~all day for much of the year, most of the time at a low flow rate (so when using a new, variable speed pump the energy savings are much greater than with the way UK systems are typically run). The Regulations about energy ratings for pumps certainly assume they run at full flow for only 6% of the time.

[dom]

Your calculated numbers pretty much tally with the estimates I made when fitting my CH.

As that time, the price premium on a quality electronically-controlled pump greatly exceeded any reasonable payback time on the electricity savings.

[SteveW]

There is far less payback than you might expect anyway - the pump is only running when you want heat and the energy used by the pump all ends up as heat, so the only saving is the difference in energy costs between electricity and gas! With the price of low energy pumps, you'd probably need the pump to last longer than the typical human lifespan to make the investment pay!

SteveW

[YAPH]

The claims I was addressing were specific to the UK market and claimed "average" savings.

[meow2222]

ISTR calculating it to be 20-25yrs to pay off the extra cost, but cant find the figures. If so, no benefit, hence why HMG are so keen to force only one option on us.

NT

[Robin]

Sorry, I should have said that I noticed (possibly as a result of scars acquired when required to work to the Alastair Campbell school of press releases) that while Mr Wilde's first para. refers to the UK market the second para. about "saving on average" does not say it is for *all* UK homeowners, or for all 1m UK homeowners who buy a pump each year, or indeed only for UK homeowners. That made me wonder if he'd looked at where big savings might be gained - but not seen it necessary to spell that out for readers.

Is there any chance the formal figures for the Green Deal will be more honest? (I ask in part as we have just decided we need to move so I have started to read EPCs for the first time and am generally underwhelmed.)

[SteveW]

The thing is, why are they so keen to force low energy pumps (at high prices) on everyone, when the waste energy of normal ones is not actually wasted? I can understand higher efficiency boilers and lightbulbs, but not CH pumps.

SteveW

[John Stumbles]

Because, from the Installer article, "they" are the pump manufacturers' lobby.

[harryagain]

Found this here on the topic. Much better explanation. Interesting.

[John Williamson]

I see they've not done the obvious thing to increase overall energy efficiency of the motor by making it water cooled and recovering the waste heat directly into the heating circuit. Doing that, it doesn't matter how much power the pump "wastes" as it's all recovered anyway.

[Andy Burns]

I thought they were all water cooled (and lubricated)?

They do precisely choose their weasel words, saying "electrical energy savings" rather than "energy savings" so they don't have to acknowledge any additional gas/oil used and "European households" rather than "UK households" or just "households" which probably agrees with what someone said earlier that european homes run on lower heat for longer each day.

[Andrew Gabriel]

Yep - if you can't sell your higher margin products on their nonsense benefits, you can make a clueless government legislate to force your higher margin products on a public which didn't need them.

[Dave Plowman (News)]

Never ceases to amaze me just how easy it is to con politicians/civil servants about such things even vaguely technical.

[dom]

How much additional domestic insulation would be necessary to cut heating n eeds by 50W in the average UK house?

Maybe an inner flap on the letterbox?

I don't think it's reasonable for the consumer to bear the burden of a cost

-hike in upgraded pump technology, but it *is* reasonable to set an end-poi nt when manufacturers have to improve and get to the point where they can o ffer better technology at more-or-less the same price.