High gas usage

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1014 posts

Uber Geek
Inactive user

#1859312 5-Sep-2017 23:36

It doesn't seem particularly high to me. 45kg used in 6 weeks is 14kWh/day or 5400kWh/year. To go through the same amount of gas in 4 weeks is 21kWh/day or 8000kWh/year.

Edit: Actually, considering you're only using it for hot water, 14kWh gives you 230L/day of 55°C water (assuming incoming water temperature of 12°C and 80% energy efficiency). That does seem a lot.

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deonb

3 posts

Wannabe Geek

#1859362 6-Sep-2017 08:29

That does seem very high...

Similar setup, normally 2 people, we use gas for stove top as well as continuous flow hot water without a temp control, (2x 45KG bottles)

We've been in our house since November last year.

- 2 new bottles end of November

- Bottle ordered 18 April

- Bottle ordered 10 July

We had a house full over Christmas (4 adults, 2 Kids) , and then again over April/May (4 adults, 3-4 kids depending who was visiting).

I'd be getting someone in to check for leaks.

Paul1977

4785 posts

Uber Geek

#1859582 6-Sep-2017 12:10

Oblivian: And unless you are with a junk provider, the bottles are serialised weighed. They should credit the fill difference.

With Contact Rockgas, so I will query about this. I don't recall ever seeing any refunds.

Paul1977

4785 posts

Uber Geek

#1859584 6-Sep-2017 12:12

deonb:

I'd be getting someone in to check for leaks.

You mean water or gas leak?

We can't smell anything, but I might contact the installer.

MikeAqua

7619 posts

Uber Geek

#1859596 6-Sep-2017 12:19

Looks like a text book seasonal temperature effect to me.

Mike

Paul1977

4785 posts

Uber Geek

#1859604 6-Sep-2017 12:24

MikeAqua:

Looks like a text book seasonal temperature effect to me.

I suspect you're right, but the usage still seems very high for just the 2 of us.

I arranged for the installer to come out and check it. Worth the cost for peace of mind, and if they find something wrong then I would assume they would need to fix it at their cost as the install is less than a year old.

darylblake

1145 posts

Uber Geek

Trusted

#1859651 6-Sep-2017 12:58

I did the maths. If you use less than 5 bottles per year, then you are better off on bottles.

More than 5-6 is roughly the same as piped gas.

More than 6 45KG bottle changes per year. Its cheaper to get gas piped.

Sounds like you having long showers. Are you sure your dishwasher/washing machine is not drawing a lot of hot water too?

Have you checked for leaks?

deonb

3 posts

Wannabe Geek

#1859666 6-Sep-2017 13:16

Paul1977:

You mean water or gas leak?

We can't smell anything, but I might contact the installer.

Gas leak, might not smell anything if an outside section? not sure how your pipes run...

geoffwnz

1271 posts

Uber Geek

ID Verified

#1859684 6-Sep-2017 13:31

Paul1977:

We don't have temperature controls in kitchen or bathroom, it is set at the unit to 55 degrees and we just mix in cold to get the desired temperature.

Not sure,but would it be worth getting a temperature controller fitted?

I use 55 degrees for washing dishes and some laundry. Showers I set to 42 and leave the mixer maxed. Was pointed out to me when I used the same default of 55 for everything that heating the water past where you need it then adding cold to bring it back down was wasting gas. Someone better than me at the physics can probably calculate the cost difference and the payback for getting a controller fitted. :-)

MotorDrive Rallying

Suckerpunch

124 posts

Master Geek

#1859696 6-Sep-2017 13:39

My refills for a household of two adults, with gas for hot water and cooking.

Refils:
20/07/2017
08/06/2017
02/03/2017
06/01/2016
10/10/2016
27/06/2016
30/03/2016

Water configured to 42-43 degrees for majority of time. Potentially slightly hotter in the winter.

Sometimes water set to 50 for dish washing.

Cold washes for washing machine.

Oblivian

6946 posts

Uber Geek

ID Verified

#1859697 6-Sep-2017 13:40

Paul1977:

Oblivian: And unless you are with a junk provider, the bottles are serialised weighed. They should credit the fill difference.

With Contact Rockgas, so I will query about this. I don't recall ever seeing any refunds.

Don't quote me on it. But you see them zapping away on/off so there has to be some sort of end to end checks going on. Potentially see a lower fee vs credits *shrug* may also work on a 'make sure its empty cause we charge same regardless' scheme

Paul1977

4785 posts

Uber Geek

#1859705 6-Sep-2017 13:56

deonb:

Gas leak, might not smell anything if an outside section? not sure how your pipes run...

All the gas pipes for the water are outside, but one running to kitchen (which isn't used) goes under the house.

They are coming out on Friday to check for leaks, and I think It'll get them to install a shutoff valve to the pipe going to the kitchen while they are there - regardless of anything else it makes sense to me to be able to shut off gas to the kitchen separately.

nickb800

2699 posts

Uber Geek

Trusted

#1859952 6-Sep-2017 20:42

geoffwnz:

Paul1977:

We don't have temperature controls in kitchen or bathroom, it is set at the unit to 55 degrees and we just mix in cold to get the desired temperature.

Not sure,but would it be worth getting a temperature controller fitted?

I use 55 degrees for washing dishes and some laundry. Showers I set to 42 and leave the mixer maxed. Was pointed out to me when I used the same default of 55 for everything that heating the water past where you need it then adding cold to bring it back down was wasting gas. Someone better than me at the physics can probably calculate the cost difference and the payback for getting a controller fitted. :-)

I'm not sure that you are wasting gas. If you are mixing 55deg water down to 42deg by adding cold water, then you are using less volume of hot water. If you are using straight 42deg water, then you are using a greater volume of hot water. There might be some efficiency issues (what temp does the gas system burn most efficiently at?) but in general it comes back to the laws of physics - you can't destroy energy.

richms

26418 posts

Uber Geek

Trusted

Subscriber

#1859984 6-Sep-2017 22:00

more would be lost in the pipe from heater to shower at a higher difference from ambiant. Not sure what the flow would be there too, that would have an effect on the efficiancy of the heater along with the amount of rise it is adding. In winter I would expect twice the consumption since about twice the temperature rise needed for the incoming cold to what comes out the shower head, regardless of where it is mixed etc.

Richard rich.ms

Aredwood

3885 posts

Uber Geek

#1860529 7-Sep-2017 19:40

It will be slightly more efficient to use a controller, and have the heater outlet temp set to exactly what you need in the shower. Partly due to pipe losses, and partly due to the heat exchanger inside the water heater running colder, meaning more of the heat from the burners gets transferred to the water. I can't calculate if you would save enough money to pay for the cost of installing a controller though.

Also a properly installed twin bottle LPG setup shouldn't have any efficiency loss when 1 of the bottles gets low. As a properly functioning changeover regulator will draw gas from the reserve bottle to topup the flow from the main bottle, if the main bottle can't provide enough gas.

And for those comparing gas usage - check your shower flow rates. If person A has a 9L/min shower, and person B an 18L/min shower. No surprises that the person with the 18L per min shower will use alot more gas.

Also @Paul1977 get your gasfitter to recommission your water heater while they are onsite. This means checking the gas inlet pressure at max flow. And checking the burner pressures at forced min combustion and forced max combustion. Even though the installation instructions for most units don't say you need to do this for a new install. I always do it whenever I install a continuous flow heater. And If I get asked to service or repair one. As if the pressures get too far out of adjustment, you can get unstable outlet temperatures. And in extreme cases, the flue gasses smell of raw gas. (I have has callouts for gas leaks due to someone smelling gas, where the only thing wrong was a water heater that needed adjustment).

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