Help me understand my hot water system!

Terr_2

I'm hopelessly confused about my hot water system.

It is an unvented system with a hot water cylinder. The cylinder has a switch which I leave on (it has no timer.)

My water is obviously heated by the boiler and then stored in the cylinder. I have the water on for two hours in the morning and two hours at night.

What I find strange is that since I'm the only person living in the house, there should be plenty of hot water at all times but I frequently find that if I take two showers a day (once in the morning and one at night) as well as do a little bit of washing up in the evening, there is no hot water at the end of my second shower!

My question is; does this seem normal? Even if the boiler wasn't heating up enough hot water for 2 showers and some washing up (it heats for 4 hours total each day) shouldn't the cylinder be topping up the temperature of the stored water regardless?

matelodave

What sort of boiler have you got?. If the tank has a switch, are you using the immersion heater as well or instead of a boiler.


Where is the immersion heater situated in the tank - at the bottom, half way up or at the top. A photo or two would help.


Have you got E7, how do you heat your place - gas central heating or electricity - storage heaters, panels heaters etc

Rubidium

Terr wrote: »

I'm hopelessly confused about my hot water system.

It is an unvented system with a hot water cylinder. The cylinder has a switch which I leave on (it has no timer.)

My water is obviously heated by the boiler and then stored in the cylinder. I have the water on for two hours in the morning and two hours at night.

What I find strange is that since I'm the only person living in the house, there should be plenty of hot water at all times but I frequently find that if I take two showers a day (once in the morning and one at night) as well as do a little bit of washing up in the evening, there is no hot water at the end of my second shower!

My question is; does this seem normal? Even if the boiler wasn't heating up enough hot water for 2 showers and some washing up (it heats for 4 hours total each day) shouldn't the cylinder be topping up the temperature of the stored water regardless?

You are using up the contents of your hot water tank, which is typically 120 - 140 litres, how long are your showers?

You could switch the immersion heater on 24/7 and it's thermostat will cut off when the pre-set temperature is reached.

Using it that way you would be paying to heat the water that has been used and keep the tank topped up with hot water.

teddysmum

My hairdresser was commenting on something similar, a few weeks ago, but she knew why she had a problem.

Her family of four adults moved from a house with a combi boiler, to an older property with a storage tank and she said she couldn't wait to get a combi installed.

She said that when one person used a larger amount of hot water (bath or shower) the next had to wait for some time or make do with warm water, as the used hot water was replaced by cold, thus cooling the contents of the storage tank, so no instant hot water for those not first in the queue.

Terr_2

matelodave wrote: »

What sort of boiler have you got?. If the tank has a switch, are you using the immersion heater as well or instead of a boiler.


Where is the immersion heater situated in the tank - at the bottom, half way up or at the top. A photo or two would help.


Have you got E7, how do you heat your place - gas central heating or electricity - storage heaters, panels heaters etc

Thanks for your reply. The boiler is a Vaillent. It was installed in 2011 a year before I moved into the house. I am not using the immersion heater instead of the boiler. The water itself is being heated by the gas boiler. The immersion heater is switched on 24/7. My reasoning is that it will top up the heat if the temperature falls below what I've set it to.

The heating element is at the top of the tank.

I'm not on E7. House is heated by the gas boiler, regular water filled radiator panels.

cameltoe wrote: »

You are using up the contents of your hot water tank, which is typically 120 - 140 litres, how long are your showers?

You could switch the immersion heater on 24/7 and it's thermostat will cut off when the pre-set temperature is reached.

Using it that way you would be paying to heat the water that has been used and keep the tank topped up with hot water.

Thank you for your reply, I really appreciate it!

I take one 5-10 minute shower in the morning. Then I'm gone all day. When I get home I'll do the washing up and take another 15 minute shower before bed.

The immersion heater is already turned on 24/7 so that it can retain the water temperature to the setting on the thermostat.

macman

It's insane to use the immersion at all if you have a gas boiler-heating by immersion is costing you about 300% more than by gas. Reset the programmer to give you a longer water heating time if necessary. You appear to be running the hot tank to zero and then the programmer is not properly set to allow it to reheat until the next morning or evening cycle. Typically set it to start about an hour before you need the hot water.
The real problem may be that the tank is undersized for your needs though.

HappyMJ

Terr wrote: »

Thanks for your reply. The boiler is a Vaillent. It was installed in 2011 a year before I moved into the house. I am not using the immersion heater instead of the boiler. The water itself is being heated by the gas boiler. The immersion heater is switched on 24/7. My reasoning is that it will top up the heat if the temperature falls below what I've set it to.

The heating element is at the top of the tank.

I'm not on E7. House is heated by the gas boiler, regular water filled radiator panels.




Thank you for your reply, I really appreciate it!

I take one 5-10 minute shower in the morning. Then I'm gone all day. When I get home I'll do the washing up and take another 15 minute shower before bed.

The immersion heater is already turned on 24/7 so that it can retain the water temperature to the setting on the thermostat.

15 minute shower!! No wonder you're running out of stored hot water. What are you doing in there for 15 minutes? Just get in there get yourself wet, get a bit of soap in the essential regions, scrub a bit, rinse and get out. 5 minutes max. You would be better off in the bath if you want to spend 15 minutes in a shower. My shower uses 15 litres per minute so therefore 15 times 15 is 225 litres of water. Half would be cold water and half hot water so it's no surprise you've run out.

Any alternative will be expensive. The cheapest - You could replace the cylinder with a larger one. There are cylinders that are much larger for your "needs".

You could replace the cylinder and current boiler with a combi-boiler.

You could install an electric shower.

I would set the programmer to heat the water 24/7. It won't cost much more than just 2 hours in the morning and 2 hours in the evening as the thermostat will stop the boiler from overheating the water. It may not give you much more than 15 minutes in the shower but you'll have a full tank of hot water within 30 minutes of finishing your shower.

edit: Turn the switch to the immersion off. It's a waste of money. That switch is only used as a backup when the boiler is out of action.

[Deleted User]

"Two showers every day " ! why ?..Have a google at "showering every day is bad for you ", and this is coming from shower mad Americans. A Daily Mail survey also revealed that two thirds of women don t shower every day.. They say just a quick flannel of the "grosser " areas is all thats needed and frequent hot showers is bad for your skin causing dermatitus and eczema. A shower once every two or three days is the recommendation, with flannel rub down on non shower days. The social norm these days of daily showers is the main cause of Eczema. Daily hot showers wash off vital oils and good bacteria ( say the scientists ).

Robin9

A bath a week - whether you need it or not !

System

I shudder when I read posts about changing boilers etc. Unvented systems are usually installed in properties with multi outlets to provide a constant flow of hot water. Unvented hot water tanks have 3 thermostats as standard. One is connected to the immersion heater and I agree with other posters that heating water in this way is a last resort (i.e., the gas boiler has failed).

In normal use, a thermostat controls a motorised valve to the hot water cylinder. When this reaches the selected temperature, then the valve closes and the boiler stops heating the HW tank. Draw some water off and the valve opens and the boiler comes on. The thermostat temperature is selectable: I have mine on 60C. To protect the system, the normal operating thermostat is linked in series with a TOPStat: mine is set at a notional 85C. This is to prevent an exploding unvented HW tank. The setting on this thermostat cannot be changed.

My HW comes on twice a day from 0630 - 0900 and 1630 to 2000: it is not heating continuously during this time. On average, for cooking and HW heating we use about 12kWhs of gas a day: about 36p plus standing charge and VAT. 12kWhs of electricity would cost me 3 times more.

matelodave

As said above, standing in a shower for 10-15 minutes will use up all your hot water. Most people think that a shower is more economical than a bath and it can be if used properly.

Get a lowflow shower head or ask your water company for a flow restrictor to reduce the flow. Ours does around 7 litres a minute but some can be as high as 15 lpm.

We only heat our water for about 1.5 hours before we get up in the mornings and that gives us enough hot water for both of us to shower in the mornings, all we need for washing up during the day (although most of it goes in the dishwasher) and another shower each if we need it in the evenings.
I actually spend just under two minutes (15 litres) in the shower and my wife less than five (30 litres).
We also only heat the tank to 45 degrees so use very little cold water mixed in. We've got a fairly large 200 litre hot tank although nowadays many tanks are only around 150-180 litres so easily emptied in 10 minutes

Don't let water run down the sink when washing or rinsing stuff (especially hot water). Use cold water for rinsing (including your hands) as every time you run off a couple of gallons of cold to get the hot through to the taps you leave the same amount of hot water sitting in the pipes to get cold.