Length of time to heat up water?? How to save money on gas

[docburgess]

Hi,

Just looking at reducing energy usage and I was wondering about whether I have my boiler on for too long on the timer.

I have a 12 month old Worcester Greenstar 30CDi (which I am v.pleased with), hitched up to a Megaflow CL170HE Unvented cylinder.

The heating is currently off for the Summer. However, we are still using hot water. In the family we use hot water to wash up - maybe x2, x3 daily and kids have a bath every day, and hot water to wash in the basin during morning and evening. The shower is an electric one.

How long should I be putting the timer on for to heat up the water. It is currently on for 2 hours in the morning (6.30 - 8.30) and 2 hours in the evening (5.30 - 7.30) in the evening.

Also, with the megaflow what kind of shower could I have that isn't electric - something a bit more powerful??

Ta XX

 

[big-all]

reduce the time by half an hour then after a week decide if the water is hot enough
reduce by further 15 min incrimets every week untill the water finnishes up not hot enough then add a further 15mins to the heating for period before it got to cold

also consider reducing the tank stat by 5 degrees for the gas if it has one

 

[kevplumb]

the boiler will only cycle on the stat anyway

Also, with the megaflow what kind of shower could I have that isn't electric - something a bit more powerful??

get a decent mixer shower

you will need to plumb in a hot feed as well tho

 

[Mr Smyth]

In the summer I don't even time mine to come on in the the afternoon.

We all shower in the morning. It is timed to come on 1/2 hr before we get up, just 1.5 hr in total.

Unvented cylinders are very well insulated. We still have hot water at 10pm. If we do use it up I just advance it on and then off.

I am amazed at the number of customers who have the HW on constant saying that they want HW at anytime. I don't thing they understand the storage element. I will often advance mine off if I hear the boiler cycling.

In these energy conscious times I think a wiring set up that just heated the HW till the stat made, then not again until later that day would be a good idea.
It would be pretty complex with relays etc, but possible

 

[mysteryman]

... that is the way it should be done. Set the cylinder thermostat to about 50C. The boiler thermostat needs to be higher. A cycling boiler on water heating suggests control faults or errors.

 

[Steve]

I live on my own. I just turn mine on at 5pm, wash up and shower at 8pm after I switch it off, and by 6am when i get up, the water is still slightly warm for a shave.

The boiler only runs for about 30 minutes, and I get a full tank of hot water.

 

[D_Hailsham]

... that is the way it should be done. Set the cylinder thermostat to about 50C. The boiler thermostat needs to be higher. A cycling boiler on water heating suggests control faults or errors.

The cylinder thermostat should be set to 60C. This is to prevent the growth of legionella bacteria, which causes Legionnaires Disease, in the water.

See //www.diynot.com/forums/viewtopic.php?p=1141649#1141649

 

[bengasman]

Provided your cylinder and boiler are installed to spec, your savings from limiting the boiler on time will be absolutely minimal.

Don't take too much notice about the legionella warning either, the danger is infinitesimally small.

If you want to save money, just use less hot water.

 

[D_Hailsham]

Don't take too much notice about the legionella warning either, the danger is infinitesimally small.

The probability of catching Legionnaires Disease may be small (550 reported cases in 2006) but the number of fatalities is relatively high (52 in 2006), which is about 1 person in 10.

There are now regulations, that apply to hospitals, offices etc, which require cold water to be maintained below 20C and hot water above 60C in order to prevent an outbreak of Legionnaires Disease.

 

[5TIMES]

I thought legionnaires bacteria was created around 20c-45c ?

 

[D_Hailsham]

I thought legionnaires bacteria was created around 20c-45c ?

Agreed, that's the temperature range where they multiply.

How water temperatures affect Legionella:
[code:1]
70°C to 80°C - Disinfection range
66°C - Legionella die within 2 minutes
60°C - Legionella die within 3 minutes
55°C - Legionella die within 5 to 6 hours
20°C to 45°C - Legionella multiply
20°C and below - Legionella are dormant[/code:1]

 

[vulcancontinental]

A couple of observations:

I'm not sure the number on the cyl. stat. 50 or 60 is particularly relevant when recalling the various heights the cylinder sats are actually fitted on domestic cylinders. I know they're supposed to be around a third of the way up but often are anything but. That fact alone plus rubbish insulation, loose fixing straps, inherent inaccuracies in domestic cylinder thermostats and the thickness of the datum lines and numbers will give false readings.

My own opinion when asked is that hot water should be hot enough to get grease off plates and too hot to run hands under without adding cold so children are encouraged to put the plug in and add cold.

The reason special consideration is given to hospitals and offices is because the occupants of the former are at risk (as are those in old peoples homes) with lower resistance to infection and in offices long runs of hot and cold water lay static in warm ducts over weekends given the opportunity of bacteria to multiply.

52 fatalities in 2006 is 1 in 1,153,846

Just got in from a tough day at work after waking up at 4:30 this morning and unable to get back to sleep so am feeling a little grouchy. Let me be, it'll pass

 

[bengasman]

Don't take too much notice about the legionella warning either, the danger is infinitesimally small.

The probability of catching Legionnaires Disease may be small ...

The amount of casualties from legionnaire's disease for this type of dhw supply last year, was pretty much the same as the year before: roughly zero.
Scaremongery, nothing else

 

[Axel]

Well, when I joined the French Foreign Legion, we were all dropping down from the old Legionnaires disease all the time. Must be those continental water heaters...

 

[JohnD]

make sure the pipes between boiler and cylinder are very well insulated

you might consider having a summer cyl stat and a winter cyl stat (I do that, my summer stat is 1/3rd down from the top and my winter stat is 1/3rd up from the bottom. It gives enough for a bath as the added cold water is not very cold (I have a loft tank). However the cylinder coil will heat the whole cylinder before the upper stat clicks off; it just doesn't come back on until a lot of it has been used. This stops the boiler running frequently to top it up. This doesn't matter in winter as the boiler will be running more frequently.

The timer goes off in the moring after breakfast, and comes back on before tea. The cylinder is ample for odd washing between times.

Use the timer and stat, don't waste your time switching it on an off like an electric fire.

BTW my gas usage in summer is only about 0.4 metres/day, but in winter it can be 10 m/day, so it is much more important to look at efficient insulation and heating control that to fart about with a few pence of hot water.