Heating my hot water via a new Valiant Aerotherm plus Air to water system

k_bagpuss

Hi Y’all! I have recently had a new central heating system put in with a new Valiant Aerotherm Plus air to water system. I also switched to the Octopus Go tariff which drops to 5p per Kw from 00:30 until around 5am so this is currently when my hot water is programmed to switch on. Am I better to also have the tank charging through the day to maintain the temperature or am I doing the right thing by charging when it’s cheaper to do so?

wittynamegoeshere

Assuming your water tank's very well insulated, why would you heat it while the power costs more?  Definitely heat it while it's cheap, probably pre-heat the house in the early morning too, as heat pumps usually take a lot longer to heat the house than gas or oil would.

matelodave

As above, just heat the tank when the energy is cheapest and then try to make sure that you dont use it all.

We only heat our for a couple of hours overnight and it keeps us going right round until the next heating cycle.

I dont dont see any real benefit in having an off-peak tariff as we are heating the place during peak times and the stats are set back overnight. Our hot water only takes around 2-3kwh a day whereas heating can be as much as 50kwh/day during peak times when it's everso cold.

wittynamegoeshere

Very useful to hear some typical running costs for a heat pump, we're about to head down this road.

That's about what we were spending on electric heaters last year, but only heating selected rooms and not very warm either.

No gas available, so it's oil or a heat pump.  Not interested in wood or coal - far too much mess, hassle and toxic smoke.

matelodave

TBH if you've already go oil then I wouldn't change it as oil is still cheaper than heating with a heatpump.

However if you are starting from scratch then a heat pump is well worth considering but make sure that the whole system is properly designed and you learn how to use it correctly. They are different to running a boiler.

We replaced storage heaters with a heatpump and underfloor heating some eleven years ago and we've been more than happy with it.

wittynamegoeshere

We've got nowt at the moment, just freestanding plug-in electric heaters.

We bought the place after someone replaced the previous gas-tank powered radiator system with scammy electric radiators, the sort of thing where they make all sorts of ridiculous claims.  I don't even use them, they have a pump in each one that all make awful noises, they're obviously worn out, plus they're all on external walls so will be wasteful to use.  Sadly they chopped off all the existing radiator pipes when fitting this rubbish, so we're starting from scratch now.

I'm considering pulling up the concrete floors in the main rooms and putting in insulation slabs and underfloor heating.  The existing floors have sagged and are cold/damp, so there would be multiple benefits to doing this.  I'd just put fat radiators in the bedrooms.

QrizB

@Reed_Richards replaced his oil system with a heat pump, from what he's said so far the costs are comparable. He's got a thread about it somewhere if you want to look, or he might pop along here and give you his thoughts now I've dropped his name

matelodave

Now leccy has increased in price it might not look quite as attractive - my leccy cost was around £1000 a year, it's just jumped to around £1700.

 We get through around 7500kwh of leccy a year of which around 3500kwh is for the heatpump and around 4000kwh for everything else

Reed_Richards

QrizB said:

@Reed_Richards replaced his oil system with a heat pump, from what he's said so far the costs are comparable. 

It has not been a year yet but I seem to be on target to use about a third of the energy I was using for central heating and hot water having replaced my oil boiler with an ASHP.  Up until 3rd October costs had been comparable to what I had previously been paying for oil.  However my electricity costs have just increased by well over 50%. But if the chart here https://www.boilerjuice.com/heating-oil-prices/ is true then heating oil prices have risen by a similar amount in the last month which means I am still broadly on par.    

Reed_Richards

I'm not sure if there is any point in mixing fat radiators with underfloor heating (I have only the latter).  You need a higher water temperature to serve the radiators so given that you have to heat some of your water hotter, is underfloor heating still economically beneficial?  If not then is the inconvenience of slow-to-respond underfloor heating worthwhile?  

wittynamegoeshere

That's why I said "fat" ones, i.e. ones that are big enough to heat the room while being merely warm rather than hot.  I understand that you lose efficiency as you increase the water temperature.

We'd have underfloor in the main living rooms, radiators in the hall and bedrooms, where I don't want it to be hot anyway.  It's a bungalow, with concrete floors throughout.

I'm still at a very early stage of thinking about it!  Underfloor heating would be great, I'd be happy to wreck the lounge and dining kitchen to put it in as they need to be severely redeveloped anyway.  But the bedrooms are pretty good already, really the floor just needs screeding.

Is there a reason why I couldn't have this sort of mix-and-match system?