Ask RiotACT: Frozen pipes on new Hot Water System

nickmof 23 July 2018 15
Ask RiotACT

Hi Rioters.

This is my first winter in Carwoola. I had a new heat pump hot water system installed replacing a 30-year-old electric HWS. The installer recommended installing in the same location 2 metres from the house with all pipes leading to the house and from the water tank underground.

Since we have recently had some big frosts – I find I get no hot water till the sun comes out. The installer keeps telling me that they can do nothing about it – apart from putting some lagging around the copper – which they originally did, but not much of.

Even with some lagging, I still have the same issue.

Can anyone tell me if pipes can freeze underground? Is it worth getting some sort of insulating cover for the HWS? Am I wrong to think that when you get a quote to buy and install a HWS that they should use local knowledge to know whether it was a good idea or not to install the type of HWS and location.

Very expensive big water tank if I cant get this resolved.

Any tips welcome.

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15 Responses to Ask RiotACT: Frozen pipes on new Hot Water System
keithjanderson keithjanderson 9:44 am 19 Sep 18

A guy near Jindabyne (much colder weather than Canberra) told me that water freezing in pipes is an issue some mornings but they work around it by leaving a tap on slightly. Because water is always moving through the pipe, it does not get a chance to freeze.
As you have a new heat pump, I’d also be concerned that the heat exchanger itself is freezing. You get hot water because the heat pump takes heat out of the ambient air – which means that the heat exchanger will be colder than the outside air. Hence most heat pump systems have an electric heater in them to thaw out the unit so that it can work. Ask the vendor/installer if your heat pump is supposed to be able to thaw itself out.

Capital Retro Capital Retro 11:29 am 25 Jul 18

Heat pump HWSs are cheap to run if they are installed as per directions (north side of house) but they only last as long as the sacrificial anodes last which is about 5 years. Then the water turns to gloop and the water input pipe fittings corrode.

On some brands it is almost impossible to replace them because of the inbuilt difficulty in accessing them and having the right tools.

At the end of the day they are not worth the electricity saving which can be equalled with a mains HWS with day/night off peak plan. Get a stainless steel one too.

Karyn Barton Karyn Barton 8:29 am 25 Jul 18

Our heat pump works nicely. Times to heat during the day. We also had an issue with no hot water recently with -7 overnight but this was because of long showers the night before and needing to use hot water before it had time to recover the next morning. Just need to be clever about water usage in the midst of winter. Pipes should definitely have lagging and I think it reasonable to expect local trades to know how to install correctly in their climate.

Jay Banyer Jay Banyer 8:13 pm 24 Jul 18

This problem is not specific to heat pumps right? The water must be freezing in the inlet or outlet pipes between the tank and the house, and a conventional hot water system would have exactly the same issue?

John Mitchell John Mitchell 8:06 pm 24 Jul 18

Here's the graph of our solar today. See the comments that I entered on Bronwyn Mitchell's post.

The blue line is power imports/exports. The green line is the solar generation. The red line is the battery charging/discharging.

Note how the blue line peaks about midday then declines.

That's the Sanden heat pump

    John Mitchell John Mitchell 8:16 pm 24 Jul 18

    I wanted to add more information. The reason why it went so long today is due to a big washing day, we were away in weekend.

    The blue line in the morning below the zero line is the Daikin multi split system running.

    I don't really care how many kWh's we import due to the fact that we export 2/3 if the generation. We get 15 cents per kWh exported.

    Our latest bill is expected to be $60.00 for the 3 months til mid July.

    Next one in October should be a credit of $150+, then the next 6 month's are free.

    This includes the supply charge. We ditched the gas hot water in January this year and no more gas & or supply charge.

    Compared to our neighbours, we are saving around $3000 pa on energy bills.

    We have also got R8 ceiling and r3 wall insulation.

    Double glazing would be great but I expect that would cost around $50000.00 and at our stage in life, not worth it.

Bronwyn Mitchell Bronwyn Mitchell 7:55 pm 24 Jul 18

We have a Sanden heat pump hot water and its timed to come on at 1 pm. That's to give our solar time to charge the battery. Looks like it's set to run at night here but you can change the program to run during the day when the ambient temperatures are higher, even without solar. It you have TOU rates, then your mid day rate will be under 20 cent's per kWh.

So check your manual and reprogram it to heat during daylight.

Jill Holt Jill Holt 6:44 am 24 Jul 18

My dad said to wrap them in a hessian bag. He always had one handy. Your dad and my dadJanet were of the same vintage

    Janet Ilchef Janet Ilchef 7:47 am 24 Jul 18

    Yep, and I don't know why more people don't think to do it when necessary

Janet Ilchef Janet Ilchef 9:32 pm 23 Jul 18

Wrap the water pipes to stop them freezing

    Lynne Audsley Lynne Audsley 9:00 am 24 Jul 18

    The pipes are underground by the sounds of it, so cant be wrapped - though I suppose wrapping pipes as they enter the house might help.

    Janet Ilchef Janet Ilchef 9:14 am 24 Jul 18

    Underground should be okay I think - it's where it comes up that trouble starts. I remember dad wrapping our pipes outside in our old house on Northbourne Avenue with hessian. I think carpet underlay can work too. For coffee etc you can always fill the kettle the night before so you can at least boil water

Meg Joy Meg Joy 9:27 pm 23 Jul 18

Housing ACT put one of these in my place (they were rolled out under a green scheme) but they were soon found unsuitable for our climate - the unit spent the whole time de-icing and water was lukewarm at best. And cost more than off peak. They were replaced very quickly.

Maya123 Maya123 12:41 pm 23 Jul 18

Pipes underground won’t freeze unless the ground freezes, such as in Arctic areas that get permafrost. There I have seen pipes running in large conduits between the houses; heated I was told. The pipe could still freeze where it comes out of the ground.

I used to live in a house where the pipes froze at -3C. I lagged the pipes and then they went to -5 before they froze. If anyone got up in the night, they would run the water to free any ice that was building up.

A pipe burst one -7 morning. Not early, as the ice had to defrost first. I rushed outside when I heard a loud bang at about 11am. Water gushing in a fountain from a pipe on the outside wall. It was an old house and the pipes where a mixture of steel and copper pipes. It was the newer copper section which burst; not the older ‘cholesterol’ filled steel. The plumber informed me he had a long list of burst pipes that day to fix.

For our climate, any exposed pipes need lagging. Rubber tube lagging can be bought, or they can be lagged the old fashioned way, with old singlets and other waste cloth. The commercial product is likely more effective though.

Matty Durham Matty Durham 10:20 am 23 Jul 18

I’m in Bungendore and we are on town water. Pipes leading in to our house must have froze over night, because we don’t have any water yet. I have lived in Canberra and surrounding region for 30 years and never seen water in to the houses freeze before, definitely a lesson for me this week.

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