Advice Needed Hot water

[Captain Jack]

We have a hot water tank, which has an immersion heater in it. It works but takes ages to heat the water from cold. It's also rather expensive on the leccy bill.

As we live in the sticks, there's no gas here so we make do with oil for fuelling the boiler. What I am wondering is... Is it more cost efficient to heat the water using the boiler rather than the immersion heater? Electricity is unlimited... Oil isn't and we have to buy it in expensive bulk quantities.

Thoughts?

 

[Lazarus]

Far, far cheaper using Oil.

Is your system already equipped with a Zone Valve and Dual Channel Controls?

I upgraded our old Single Channel Controls myself for about £25 a couple of years ago.

We keep the Boiler running for Water only even in Summer.

 

[bim]

Would totally agree with Tivu but you must always keep a head of hot water and a well insulated tank. It works out expensive when you continually heat from cold. You can now buy oil combi boilers - hot water on demand.

 

[Captain Jack]

Sorry, I have no idea what a zone valve or dual channel control is...? We have a temp setting on the immersion as well as on some thermostat thing at the bottom of the tank which is strapped around it. Is this what you mean?

The house is rented so we're stuck with what we have I am afraid.

 

[bim]

It sounds like you have got quite a basic instalation there. The thingy that is straped to the tank is more than likely a censer thermostat connected to the boiler. I think your best bet is insulate the tank well even with duvets or blankets when not being used. The only offset of this is your airing cupboard becomes cooler more of just a cupboard.

 

[DishDick]

Just a couple of thoughts. We had problems here with water heating - Solar heating coupled to immersion heater for evening heating. We stopped getting hot water, so I took out the immersion heater to check it (on these the immersion heater is at the bottom of the tank and the tank is on the roof so no problem with the water coming out. The immersion heater element was eaten away and it had been incased in about two feet of sludge that had built up over the years. Maybe you can get a plumber in to get your tank serviced (emptied, cleaned out and a new element).

Also if you are in a hard water area think about having a cheap water softener fitted to the inlet of your tank.

 

[dmaavrigdo]

According to http://www.energysavingtrust.org.uk/Energy-Saving-Trust/Our-calculations electricity is twice as expensive as oil per kwh.
We don't have the option so I have fitted a timer on the water heater so that we don't use electricity during peak hours(we have hourly billing).

 

[Lazarus]

Sorry, I have no idea what a zone valve or dual channel control is...? We have a temp setting on the immersion as well as on some thermostat thing at the bottom of the tank which is strapped around it. Is this what you mean?

The house is rented so we're stuck with what we have I am afraid.

Zone Valve is just a plumbing device that diverts the boiler water output to Heating only, Heating plus Hot Water or Water only, as directed by Timers and Thermostats.

Simple Central Heating controls normally allow only restricted functions whereas Dual Channel give entirely independent control of On/Off Timings for Water and Heating separately.

 

[Captain Jack]

Ah right. In that case yes, we have independent control of hot water and heating:- i.e. we can have heating on without hot water and vice versa. Is that a good thing? Would it be best to have both, hot water and heating, come on at the same time?

Also, how do I maintain a head of hot water in the tank as bim says?

 

[Lazarus]

Independent control is good.

As far as whether you actually have both CH and Water on at the same time is more a matter of preference than efficiency: If the HW Cylinder is up to temperature, then the Tank Stat. will cut off further heat input anyway. Ditto Room Stat and Radiators.

And as for the head of Hot Water, I suspect that what was meant was what you've got: A Hot Water Cylinder that is well-insulated and equipped with a Tank Stat. strapped to the Cylinder.

The head is just pressure from the Cold Water tank in the loft which allows the Cylinder to be able to express Hot Water when demanded and also tops it up.

So the basic answer to your OP is to use the CH Boiler for Hot Water throughout the year and only ever use the Immersion Heater when you run out of Oil!

 

[Captain Jack]

Right - got it! Thanks! Oil usage is quite high here and we used up about 700 litres since October - but didn't use oil at all for hot water.

Next house will need to have a combi-boiler. Much more efficient....

 

[Lazarus]

700l is by no means excessive.

We normally use about 850 over a similar period.

But our consumption from May - September, for Water only, is barely noticeable.