Immersion vs winter boiler use

[Kes]

We have an oil boiler with gravity-fed flow and return to the h/w cylinder, and pumped c/h. We have the immersion heater on continuously for h/w in the summer, but in the winter we have used the 'free' h/w from the boiler when the c/h is on.

With oil now around 45p a litre, and a tank refill approaching £1000, my mind is now being concentrated on reducing the amount burnt as much as possible. We are, by the way, on an advantageous fixed price electricity tariff until 2010.

Would there be any advantage in having the immersion heater on in winter with the boiler supplying the c/h? In other words, would the already heated h/w reduce the gravity flow from the boiler to the h/w cylinder enough for us to notice a reduction in boiler use? I appreciate there would still be some flow (unless I fit a gate valve on the return, which might be frowned upon), and it's difficult to measure the actual amount of oil used, but any opinions/experience would be welcomed.

Rgds.

 

[bengasman]

Look at the small print and the actual price per kW-hour. Unless you have a really rare situation, the so called advantageous price is more advantageous to your supplier than to you. if you are on econonmy 7, cost is about the same IF only warming up at night. Other wise electric is about 3 times more than oil

 

[Kes]

The actual price we pay (after the first 225 units per quarter at 11p) is 7.15p inc tax per unit.

I reckon we use at the most 4 units a day for h/w for the two of us, so that's around 30p. I don't think we could have the boiler on twice a day for h/w without using at least a litre of oil each time, which is 90p. So immersion it is during summer (at least until 2010, when we will be in shock).

Going back to the question, I timed the boiler when it fired up on c/h and h/w in the afternoon on the last two days. It took 32 mins to reach termostat cutoff temp. I then put the immersion heater on in the morning, and timed again this afternoon. It took 36 mins to get up to temp, so I don't think my theory is too brilliant. Having the immersion on might reduce boiler cycling a little, but probably not enough to notice.

Rgds.

Oh yes, although we have a twin meter with night and day readings, both are summed and charged at the same rate on our bills, which suits me as we don't run much at night.

 

[bengasman]

if you want to save real money, you may want to consider improving your system. rough guess would be that at the moment, for every pound you get in heating, 50 p flies out the flue. the only thing less efficient than what you have, is a back boiler

 

[Terrywookfit]

if you want to save real money, you may want to consider improving your system. rough guess would be that at the moment, for every pound you get in heating, 50 p flies out the flue. the only thing less efficient than what you have, is a back boiler

Unless the boiler is extremely old I would expect an efficiency of at least 80%!!

 

[simond]

You might be better off changing your tariff to a low rate overnight and heating your water during this period.

A very useful device I have just bought is an Owl energy meter. It comes with a wireless clamp for the electricity meter and an internal RF display.

I have an LCD display in my kitchen showing in pence per hr how much electricity I am using. It will even display how many kg of C02 you are producing from your electrical consumption. My kids are turning lights OFF now

Costs around £50 from internet suppliers, is also known as an Electrisave.

 

[Kes]

if you want to save real money, you may want to consider improving your system.

The boiler is a Worcester Danesman 26/32, about 5 years old. I know there are more efficient boilers, but you have to weigh up the high cost of replacement against the efficency savings against the likelyhood of moving/dying. It's not on at the moment.

You might be better off changing your tariff to a low rate overnight and heating your water during this period.

The higher cost of daytime use would wipe out any overnight savings many times. In any event it would be difficult to beat our present fixed tarrif.

I do like the idea of a 'how much juice you're using' meter, but I'm too mean to splash out £50. Luckily children have scarpered, so I only have to follow my dearly beloved switching off the lights. The individual meters that can be plugged into a socket seem interesting though.

Rgds.

 

[JohnD]

I only have to follow my dearly beloved switching off the lights.

buy CFLs. Lighting uses trivial power.

 

[htgeng]

I do like the idea of a 'how much juice you're using' meter, but I'm too mean to splash out £50. Luckily children have scarpered, so I only have to follow my dearly beloved switching off the lights.
Rgds.

I understand what your saying here, but already said you are paying £1000 for an oil refill which would be better looked into than saving a few pence and riling your missus.

I would recommend you try to improve the efficiency of your existing system. The obvious points are; Upgrade from gravity to fully pumped. Invest in a boiler energy manager such as the danfoss BEM 5000.

 

[JohnD]

obviously already done the insulation and draughtproofing, fitted TRVs?