Why is my Hot Water Not as Hot in Winter?

May 07 at 12:08pm - Posted In: Uncategorized

Why is my Hot Water Not as Hot in Winter?


Ever wondered why in the first cold snap of the season your hot water system seems to be delivering lower temperature hot water or it seems to run out faster than it did before?


In Sydney the first cold snap is here. In less than a week we have seen daily temperatures go from 27 degrees to a high of 16 degrees. As a result, we have had half a dozen calls complaining that the temperature of their usually hot,hot water is now tepid or running out quickly. But why is this so?


There are several reasons for this. As the weather becomes cooler our behaviour changes. We like hotter and longer showers. So even if you don't realise it, the amount of cold water you mix with the hot water decreases, therefore, the hot water has to do most of the heavy lifting. by providing the majority of the water in the showering process. This combined with the slightly longer showers means that in a storage tank, where there is a finite amount of water preheated for you to use, tends to run out faster.


In the case of some of the instantaneous hot water heaters, they work a bit differently and it has everything to do with the ambient water temperature. These heaters work by heating the cold water up a set amount of degrees,so it is completely reliant on the temperature of the water entering the hot water system. This can be explained simply in the following example. Say that the temperature of the cold water in summer is 25 degrees (due to the weather being warmer and the pipes possibly in the sun also heating the cold water) if the hot water systems job is to heat the water up 20 degrees, the hot water will be delivered at 45 degrees. Therefore, in the winter when the ambient cold water temperature is 15 degrees and the hot water system still does the same job and heats the water 20 degrees the new hot water temperature will be 35 degrees. So, what you are feeling is right! The water is colder just when you want it to be hotter. This is the simplified version, there are other factors that come into play and not all the heaters work exactly like that, but you get the drift.


This is all complicated by the fact that it is law in Australia to have tempering valves installed or pre-set heaters that only allow the hot water to be delivered at a maximum of 50 degrees to any showers. But that is for another day.


The reasons why your hot water is not as hot in winter as it is in summer in summary


1. The outdoor temperatures are cooler so you want to shower in hotter water.

2. The ambient cold water temperature drops so the cold water you require in the shower is less meaning the hot water becomes the majority source of water causing it to run out faster.

3. The cold water start temperature affects the end temperature in some of the simpler hot water heaters.

4. In a storage tank when you draw hot water off during a shower at the same time cold water enters the system to replace the water you use. Since this water is colder in cooler months when it mixes with the hot water left in the tank it also drops the temperature of the water in the tank meaning the water will run out more quickly.


So, what can you do if you want hotter showers or the hot water to last longer in the winter?


Some hot water systems have a summer and winter mode. If that is the case, this is the time to switch it over.Often gas storage heaters and some internal gas instantaneous heaters have a dial or slide switch that allows you to increase the temperature of the water (don’t forget to turn it down again in the summer). Other electric heaters may have a thermostat that can be increased, but this will be out of site and will require the help of a plumber or electrician.


If you do want to talk this over with us, or have us check your heater please give DY Plumbers a call on M. 0408 265 798 we would love to help you.


Happy showering

Linda xx