Fixing a solar hot water controller

By Eco Guy 10:28am 1st October 2012

Fixing a broken solar hot water controller need not be that expensive

We have had a Hills Solar evacuated tube solar hot water heater for a number of years now that provided cheap hot water year round. Recently we noticed that our hot water was not as hot as we were used to it. We put it down to a cold and cloudy winter. Although once we noticed that even on sunny days there was not much hot water available it was clear something was wrong.

So under the house I go, we have a system where the hot water tank is fitted in the crawl space under the house at the end where you can easily stand. Now a quick touch test of the return pipe where it goes into the hot water tank showed there was not much heat.. Hmm, a quick look at the solar controller showed that it thought it was powering the pump, the light was on. The pump must have gone I thought, but these small pumps are very reliable. I wondered if the controller itself was to blame, so I turned it off and turned it on, then when the light came back on I could hear the relay 'click' and the pump started up. So the relay had stuck.

So thinking I might have fixed it, I left it a day and came back and had another look at it. Same thing, the light was on but no pumping going on. So this time I flicked my finger against the controller box and that was sufficient to make the relay set and conduct.

So the relay was 'shot' (very technical term). Now I got hold of the company through which I bought the system, they quoted me $125 for a replacement second hand controller or $250 for a new one. They also suggested (to their credit) that I could just replace the relay and see if that would sort it.

Wanting to avoid such expense I dismantled the controller and found the relay was a standard 12v coil with SPDT (Single Pole Double Throw) mains rated. In fact it was a rather low end relay operating at its make and break ratings (usually one has a relay with its make and break ratings well above the load, so it will last a long time). So I just unsoldered it and replaced it with a much higher rated relay from my 'stock' of electrical bits. Put the board back in and applied power and was rewarded with a nice strong 'click' and the pump was on and pumping.

Since this fix we have enjoyed again low cost hot water.

Whats the learn from this - if you find you are without hot water and the controller thinks it has the pump on, give the controller box a good flick - if it comes on, you have a bad relay which can be replaced for as little as $10..

Related Content Tags: solar hot water

Comments left

Solar Hot Water Systems Perth said:
Good thing you figure it out without spending lots of dollars. Solar hot water systems is really a great idea to used in every household.
ON Sun, 7 Oct 12, 4:26pm probably from Philippines Reply to this comment
Nkonnect said:
A very usefull and for too much needful for household plans.for house purpose its very usefull product for houseperson its very much needful product.
ON Fri, 24 May 13, 2:06pm probably from India Reply to this comment
Steven said:
Same problem hills evacuated tube system. Pump light on but no pumping. Pump not the problem. Open up controller box and press the relay, then there's clicking, and then pump starts.What relay did you use?
ON Sat, 30 Nov 13, 6:28am probably from Australia Reply to this comment
- Eco Guy said:
  Unsolder the relay and take it to jaycar to get a replacement, around $5. Your contacts have become pitted.
  ON Wed, 4 Dec 13, 11:15am probably from Australia Reply to this comment
  - Omots said:
    Thanks Eco Guy and Steven for taking the time to lodge the problem and solution. Same issue for me with my Hills Solar Controller. At first I thought it was the pump, but after tapping the controller and then the relay, I realised the problem was in the controller. Anyway, Swapped the relay with a new one from Jaycar. Now working fine. $8 is way better than a few hundred.
    ON Thu, 5 Dec 13, 10:08am probably from Australia Reply to this comment
  - Billc said:
    Eco Guy (and Omots) I know this thread is a bit old but I've no alternative . . . How can I identify the relay? There is a marking on the board of RL3 - is the relay on the reverse of this? Is the changeover foolproof? Incidentally it's a Hills Esteem system . . . Thanks.
    ON Wed, 16 Jul 14, 4:56am probably from Australia Reply to this comment
    - Eco Guy said:
      Hi Billc,
      
      The relay will be the (usually black or clear) plastic box with 8 soldered pins on it (2 for the coil, and 6 for the switch). The pins are of standard centers so an equivalent relay should fit with no problem - just take the old one to Jaycar to be sure
      ON Tue, 22 Jul 14, 7:24am probably from Australia Reply to this comment
Dsteve said:
I have a Hills Esteem II solar hws with a Er2 light on the controller and a T1 light showing - anyone know what this means. I am quoted $1375 to replace the controller and pump but I am not even sure what is wrong as the troubleshooting in the manual supplied is useless.
ON Tue, 11 Feb 20, 2:00am probably from Australia Reply to this comment
Colin Symonds said:
Our hills solar is not working red light is flashing on controller can someone tell me what this red light means thanks Colin symonds
ON Mon, 13 Dec 21, 8:33am probably from Australia Reply to this comment
Bob said:
Hi. we have an older Hills solar powered hot water system. It was in the house when we purchased the house.The hot water supply is working perfectly but about a week ago I bumped the control box and the red collector sensor light started flashing. I turned eveything off, took out the plug and switched it back on. It continued to flash. It stopped after a few days but has started again. Everything seems to be working and we have plenty of hot water. What should I do> Thanks. Bob.
ON Mon, 2 May 22, 1:02am probably from Australia Reply to this comment
Sid said:
I have same system and problem. Except I don't need to tap it, just squeezing a bit does the trick. It seems the cover has distorted slightly with time and is somehow preventing the relay operating. I've put a small clamp across the cover and it's all fine now. I'll take it apart some time and see if I can fix it properly!
ON Fri, 10 Jun 22, 11:53pm probably from Australia Reply to this comment

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