Time To Heat A Hot Water Cylinder

kidsbo

Guys,

Just built and moved into my house. Its a 4 bed house with 1 bath and 2 en suites. Its heated by LPG and has a pressurised water system. There are 2 of us living in the house only but we are running out of water when we have showers. There are no elec showers in the house. The hot water cylinder is 230L...is this too small? The shower heads are large - 8inch so maybe they are using too much water? Also it is taking 1 hr 20 mins to heat the tank. These seems like an awful long time..is it?

davidoco

A 230L cylinder would serve a family who have normal shower/bath routines.

The first suggestion I would make is that you check the device that controls the heat of the water stored in the cylinder.

If you have a pressurised system your very likely have a tank with a white cover. The thermostat can be found on the top of this tank. If you have a green covered tank it can be harder to find.

Once you have found the thermostat for the tank turn it up slightly (by 5 degrees at a time as you may not have a thermostatic mixing valve and need to ensure that you don't scald somebody at the normal hot water tap outlets) and see if that solves your problem with the shower.

A nice hot powered shower (as you have) will empty a 200 litre tank in under ten minutes. By increasing the temp of the water in the tank you might be a bit more out of it.

One hour to heat a full tank from cold would not be uncommon.

kidsbo

We have a thermostat and it is set to the max (65 deg).there is a mixing valve so as not to scald when coming from the taps.I have a white tank but the stat is towards the bottom of it.you say that a good size powerful shower will use all the water in 10 mins.I have timed our shower and it runs out in about 14 mins.my partner showers for 15 mins so that's all the water gone.is there any way to extend this other than by increasing the tank size?if not then we can't have two showers in a row..that seems crazy for a new house.heating the water for an hour just to get one shower seems crazy and expensive.any suggestions?

davidoco

kidsbo wrote: »

.any suggestions?

shower together

kidsbo wrote: »

.I have timed our shower and it runs out in about 14 mins.my partner showers for 15 mins so that's all the water gone.i

IMO having a 15 mins power shower every day is madness. The average person uses 150 litres per day not in one shower. But each to his own. I use a 1.5 bar pump on a 200 litre cylinder and it is perfectly good for showers.


If you are using a well and booster pump to provide the pressure for the hot water system you could try and turn down the pressure being produced by the booster (if possible). This would provide less of a thru put of water. If you are on mains water a pressure reducer can be fitted.

kidsbo wrote: »

heating the water for an hour just to get one shower seems crazy and expensive.any suggestions?

Out of interest do you have underfloor heating? It may be the case that your cylinder stat is set to 65 but your boiler is not heating the water to that, new condensing boilers work best (efficiently) at lower temps and may be set to say 50-60 degrees. While this is fine for underfloor, getting a cylinder only up to 50 is neither efficient nor safe for health reasons. Before you consider changing anything on the burner get a thermostat and try and get a reading for the actual temp of the water in the cylinder at the top or on the hot water outlet pipe if you can get to it before the thermostatic valve.

You can of course fit a second hot water cylinder and a zone valve/thermostat will take water from whichever is hot, or use one as a preheat for the main cylinder.

PS shower heads which create a finer spray make the water feel cold at your feet, bigger drops from the shower head are better so adjust that if you can as it causes you to turn down the shower temp thereby saving hot water.

kidsbo

I think the bar pressure is at about 3.5 bar...I'll turn that down and see how I get on.

I dont have UFH. I can get to the hotwtaer outlet before mixing vale so I'll check the temp on that. the shower spray is fixed so i cant increase that. i have a feeling a 2nd cyliner will be my only option. Even if we were only showering for 5 mins, the water would run out if we had more than 2 people in the house.

Thanks for advice. One last thing i want to confirm....taking an hour to heat 230L tank is about normal?

davidoco

kidsbo wrote: »

I think the bar pressure is at about 3.5 bar...I'll turn that down and see how I get on.

I dont have UFH. I can get to the hotwtaer outlet before mixing vale so I'll check the temp on that. the shower spray is fixed so i cant increase that. i have a feeling a 2nd cyliner will be my only option. Even if we were only showering for 5 mins, the water would run out if we had more than 2 people in the house.

Thanks for advice. One last thing i want to confirm....taking an hour to heat 230L tank is about normal?

Getting the pressure down to between 2.5 and 3 should help a lot.
Getting hotter water in the cylinder will help.
Priortise the water heating will also help.

How long to heat a 230L tank depends on a lot of things. Firstly if you have rads on at the same time as you trying to heat the cylinder it will be slower to heat. New cylinder should be your last resort. If it was really an issue you could have a hot water priority switch installed which would divert all the energy of the boiler to the hot water until satisfied, although this will mean that the rads while calling for heat will not get it until the cylinder is heated.

If you have an infrared thermometer take a reading from the outlet/flow from the burner also. If that temp is not near 65 your stored hot water will never reach that temperature.

Another issue with the speed of hot water recovery is the coil in the cylinder. Now when they are putting in two coils (one for fossil and one for solar) the coil size can be reduced. The speed of recovery of the cylinder would be directly related to the size of the coil. If you have a dual coil but no solar you chould attach the flow from the boiler to the solar coil also which would really speed things along.

eerwegtweg

Wow, 15 minute showers. This is really excessive. Have you considered the effects of this? Water doesn't just appear when you turn the tap on. There is an extensive, expensive process behind getting it to your home in a clean condition.

In Australia 4 minute showers are recommended and everybody there still manages to stay clean.

No doubt you won't mind paying the proposed €175 water charge when/if it is implemented.

If you both had 7 minute showers it could work. Or you shower quickly first and let your partner suffer the cold at the end!

I appreciate that it is annoying though to only get 15 minutes out of one tank - doesn't leave any for the washing up or other appliances that use hot water.

kidsbo

we have our own well so i dont think the water charges will apply to us. nevertheless we accept our environmental responsibilties so all our rainwater is harvested for re-use.

i have the rads and tank off sequence to speed things up a bit and that has helped. ill be interested to check the temps at the tank and at the boiler. The boiler screen tells me that it reaches about 72 deg but we'll see. I do have a dual coil cylinder but no solar so I'll look at that (i know, i know..rainwater harvesting but no solar!!!)

eerwegtweg

Apologies kidsbo for making an assumption on where you get your water.
Rainwater re-harvesting is a fantastic concept. Well done to you guys. As you say though, solar heating is the next step. Your tank will heat up far quicker if the water is coming in warm.
Good luck!

pipers

kidsbo wrote: »

I do have a dual coil cylinder but no solar

That looks like your problem, the whole area beneath the bottom connection of the top coil is never heated, therefore reducing your cylinder's stored hot water capacity way below 230 litres.

Also a 3.5 bar pump is excessive, it will pump a huge volume of water in no time.