LPG Bottles

Craig_1979

Hi, I'm looking for some help understanding LPG 4 x 47kg bottles which will be used for central heating and hot water.

It's a brand new Worcester Bosch Greenstar 24i Junior with a maximum output 24kw.

I think I've got my head around 2 bottles being used then it switches over to the next 2 bottles, allowing the empty ones to be refilled.

I have a 1950's, 3 bed semi, living room, kitchen, one bathroom and electric shower. The cooker is electric.

I know it's a difficult question to answer but roughly - how long would one bottle last? Or is there a simple way to calculate how much gas would be used per hour with the above boiler and then i could roughly calculate how long a bottle will last.

We did consider LPG bulk tank however due to other external reasons, this is not possible. It is hoped that mains gas will be arriving in the village soon or I would have considered oil but in the short term, the bottled gas appears to be the best option.

Sorry if this question has been asked before.

paceinternet

1 Kg = 1.985 litres
1 litre = 7.08 KW

You will be running 2 bottles at a time, so calculate for them being changed as a pair.
So, 2 * 47kg bottles will give you 186 litres, which is 1321 kw
Recognise the efficiency of your boiler, say 90% and you will get about 1189 kw of heating.

How many hours a day and how many kw you need for each room is for you to estimate. But at 80 w per sq metre, say total 80 sq metres, needs 6.4kw per hour.
If 8 hours per day, this needs 51 kwh per day. So 1189 kw of gas will last 25 days.

Is that a combi boiler? or Water heating to the tank?
An estimate might be 3-6kwh per day for water heating, so add that in to the above numbers.

Substitute your own numbers as necessary.

Craig_1979

Thanks for the reply and explaining it for me.

It's a condensing combi boiler and the current hot water tank etc will all be removed.

Rough calculations against our current coal use is approximately the same cost. It's more a convenience thing with 2 children and the need for hot water on demand and the plus of not having a coal fire and hot house in the summer months.

Your help is appreciated, thanks.

Craig_1979

I'm hoping someone will be able to provide further clarification regarding my original post.

When using 47 kg cylinders, do you have to have 4 cylinders with 2 connected at the same time or is it possible to have only 2 cylinders with one being used at any time?

Is it easy to convert from cylinders to bulk tank in the future?

Thanks again in advance

paceinternet

Hi,
The requirement for pairs of bottles delivering gas together at the same time, is based on the maximum flow rate demanded by your system. Not just the boiler, but any other devices using the gas as well. So, you need to establish this number. There is a limit at which single bottles can provide gas.

There is also a pipework size issue where you need to use 15mm or 22mm to meet the flow rate.

The regulator on the bottles will have a flow capability, so you need a suitable size unit to meet the flow needed by your system.

Finally I guess you have to consider how often you will need to change them, and if using pairs makes that more acceptable.

How much are you expecting to pay for 47kg bottles in your area?
Locally to us, they do not seem to have reduced their prices from the highs of last year.

munchings-n-crunchings

Hello Craig,

I decided to go for the 4x47kg bottle option, rather than the bulk storage tank.
I was given the option of having a 2 way changeover valve and 2 bottles, but I would be forever ordering, so this option made sense.

It's a little more expensive this way, but I find the budgeting more affordable.

2 bottles during last years winter, lasted me 5 weeks.
That's with it being on from 06.30 to 09.30 and 16.30 to 22.30, running at a temperature of 22 degrees. Likewise, I live in a 3 bed semi.

I am in Notts, and I buy 2 x 47kg bottles for £76.
The come and take the old ones away and fit th new ones, and then reset the indicator to the new bottles.

Regards
Munchie

Craig_1979

Thanks again for the replies.

I've decided just to go ahead with the installation and will give the company a call later on to arrange a date.

I was hoping to have the 4x47kg option but due to space, waste pipes etc at the back of the house, we have room for 2x47kg. I realise we'll constantly be placing orders.

I think we'll see how the system works this winter and possibly look at an underground bulk tank next summer. Due to a pylon the above ground tank would have to be sited in the middle of the garden to the rear or at the front. We have a garden to the side and driveway which holds 5 cars so an underground tank would be the best option at the top of driveway as we don't require 5 car parking spaces.

I've checked with a couple of suppliers locally and they have quoted between £75 to £90. One of our friends has offered to at least match the best price we receive as he owns a local business which supplies gas related items.

I am also looking at cavity wall and loft insulation, so hopefully this winter will be a warmer one with a lot less hassle without coal.