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Hot water system maintenance

Experienced Contributor

Hot water system maintenance


Hi everyone,


This is probably a silly question, but do hot water systems need to be serviced?


All of a sudden we are running out of hot water after a short period of use. 


We have only owned the house for 18mths and it doesn't look like an old system...I just don't want to wake up to no hot water one morning during winter!



Experienced Contributor

Re: Hot water system maintenance

What kind of system do you have @KingStreetReno? Gas, electric, solar? And is it an "instantaneous" system that heats water as you use it, or does it have a storage tank? 

Experienced Contributor

Re: Hot water system maintenance

Hi @AHoy, it's a Rheem gas hot water system. I thought it was instantaneous as we never ran out of hot water, but all of a sudden we seem to be!

Trusted Contributor

Re: Hot water system maintenance


Hi, if your Rheem is a smallish rectangular box then it's instantaneous, or if it's a large cylinder then it would be storage HWS.

I'm guessing it's instantaneous, & that the flame is being cut off by an out of adjustment or faulty gas regulator. Their purpose is to shut off the flame, if it thinks that the water flow rate is too low.

It may be as simple as tweaking the set screw, or it could've been brought on if you have hard water, & scale has built up in the water path of what looks like a cylindrical car radiator, the heat exchanger.

We had a gas instantaneous HWS, & I was able to just tweak the set screw, but if you're not confident, call a gas fitting plumber.

Another plan of attack, is to use your temperamental HWS as a kickstart to go Evacuated Tube Solar HWS. ; ) That's what we have now, & we love it.

Oops, just remembered, all HWSs have Pressure Relief Valves (brass body & a tin coloured lever which looks like a trigger), & they need to manually exercised every 6 months.

Budding Contributor

Re: Hot water system maintenance

Yes, as soon as I get some spare dollars, Evacuated Tubes are going on all my domiciles. Little bit expensive to start, but most efficient and easy to scale back in summer (PVC pipes cut in half to cover the tubes)

Also thinking about some HW storage, using older electrical HWS storage cylinders (for the insulated storage, not powered) and a little solar powered pump to get the water up to the tubes and back into the storage tanks.

You see these cylinders on the kerb often, I assume the elements have given out (calcified or otherwise) but usually still water/pressure proof, so they will be good storage (even if it's a pre heating condition).

For those that aren't sure of what I'm saying - If you get some heat into the water before the final heating, then your water heater isn't working so hard. Imagine if you have supply water temperature of 12 degrees and you want 65 degrees water at the end, then the tempreature difference is 53 degrees (water takes 4.2kW per kilo per degree to heat - so if you heat a kilo of water from 12 to 65 degrees it will take 222 kW of energy - if this is done in one hour, it will require 222kW/h - Maybe I'm going too deep with the theory??)

Anyways, even if your solar panels can increase the water in your storage (say 350 kilo's) by 30 degrees, then you save bucket loads of power required to get it to your required 65 degrees.

The main energy needs in a house/domicile is water heating and space heating (environmental heating for your comfort)

The easiest savings can be made with water heating.

Something else to keep in mind, your storage hot water system (HWS) must be a minimum of 65 degrees, but with the latest laws requiring a 'tempering' valve (which mixes cold water with the hot water) to finally supply water at a maximum of 55degrees, then inefficiencies are being built into the system.

This becomes quite deep and requires some deep understanding to get a grip on what is happening in the HWS - so some 'preheating' of the water is quite valuable.




Community Manager Jason
Community Manager

Re: Hot water system maintenance

Thanks for sharing @Kev.


You might also be interested in this previous discussion on Workshop - Options for replacing gas booster on solar hot water system



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