LPG yo heat water

Energy28

Hello
After lots of advice regarding my storage heaters and the cost... I am now looking to swap from E10 to E7 (thanks everyone that helped me with this decision). 
I now have a question I have tried researching without any luck. As I have storage heaters and if I move to E7 then my main concern is having enough hot water without the afternoon and evening off peak. My meter does not have a boost button. I have a friend with LPG heating and my question is if its possible to have LPG just to provide hot water and nothing else. 
I see there are 3 types of LPG compatible boiler,q some with water tanks, but not sure what would be the best. I am putting a new shower in a.month or so, so wondered if I would only need a thermo static one if I had a LPG boiler.
Are LPG boilers cheaper to run than electricity?
Would there be a certain size I would need just for water.
I am in a mid terrace with no space for a tank, can you run a boiler off cylinders?
Any guidance, gratefully received.

Gerry1

It would probably take several decades to recoup the cost of the LPG boiler installation, especially if you're using cylinders which are more expensive.  Basically you need to go the whole hog, it's CH+DHW or nothing.

Check your existing immersion heater installation.  Does it have one immersion heater or two?  It would be unusual to have just one heater on a switched supply.  The best is to have two heaters, the lower one on the switched supply, the upper one on a 24h circuit, preferably with a timeout so that it can't be left on permanently.  Second best is a 24h supply and a timer that shadows the E7 times, but woe betide you if it gets out of kilter and the bills rocket.

Don't put in an instantaneous electric shower (unless you only shower during those seven hours).

Energy28

Thanks Gerry1, I'll avoid the LPG then.
Our water tank only links to the off peak 10 hours and does not have any other immersion. Is that unusual? Is there a better option than what I have?
Sadly we need a shower, the hot water from the tank for baths, is just nit enough, especially now my sons are having to complete uni from home.
Thanks 

Gerry1

If all consumption is charged at the lower rate during the off peak hours (it is on E7, not sure about E10) then the simplest solution is to feed the immersion heater from a 24h supply and install a timer next to the hot tank.  Program it so that it only heats up during the off peak times.  If you run out of hot water, just press the Boost button to get an hour or two at day rate.  Available from Horstmann and others.  Make sure it has back up so that its clock isn't affected by power cuts; a simple motorised one is risky.  It will still be suitable if you change to E7.

matelodave

Energy28 said:

Thanks Gerry1, I'll avoid the LPG then.
Our water tank only links to the off peak 10 hours and does not have any other immersion. Is that unusual? Is there a better option than what I have?
Sadly we need a shower, the hot water from the tank for baths, is just nit enough, especially now my sons are having to complete uni from home.
Thanks 

You could possibly fit a larger hot water tank with two immersion heaters, one for normal off peak and the second for boosting during peak hours if  necessary - it would be a lot cheaper than installing an LPG boiler. You could also try to teach them that they probably don't need a bath or even a shower every day unless they are doing something pretty physical. Studying doesn't really work up much of a sweat.

However, even if they do, you can economise on how much water you get through by fitting an eco shower and limiting the amount of time that gets spent in there.

A bath can get through about 80 litres or water (more if its a big one or you fill it right up), a conventional shower at 10 litres/min for ten minutes could easily get through 100 litres, whereas an eco shower head or one with a flow restrictor at 6lpm for five minutes is only 30 litres.

I can manage a thorough shower and wash my hair in less than two minutes.

You can also economise by not wasting hot water by rinsing stuff (including your hands) under the hot tap. using a bowl and not taking short drawdowns of hot water. The half a gallon or so of cold that you drawdown to get the hot water flowing leaves a similar half a gallon or so in the pipework to get stone cold until the next time you do it so its pretty easy to waste several gallons of hot water every day without really trying.