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Should I change my old gas boiler over to Heat Pump?

28 Dec
Should I change my old gas boiler over to Heat Pump?
Hydronics

Why retrofit your gas boiler with a heat pump?

It is opportune to change your old gas boiler over to Heat Pump if your old gas boiler is heating hydronic underfloor coils or radiators and is more than 10 years old. Your hydronic underfloor coils or radiators will likely have useful life left and can be reused with a new heat pump. You can also power your heat pump with solar panels to make very low heating/cooling cost. Heat pumps can be reversed in summer to provide cooling through your hydronic system. This works best with an underfloor hydronic system in conjunction with ceiling fans but will have a cooling effect running cool water through your radiators particularly if you use a fan to blow air across the radiators.

If you have radiators, you will need to flush out the hydronic water and remove metal particles or sludge from the hydronic water that may have built up over time. Siddons Solar hydronics recommends you install a magnetic metal filter such as the Fernox TF1 Total Magnetic Filter, to trap metal particles coming from the steel in the radiators over time to ensure your system remains clean going forward. If you have underfloor coils, you should also flush out the hydronic water and remove any mould or sludge that may have built up. Learn more about magnetic filters by clicking here.

How to retrofit the gas boiler with an electric heat pump?

You can replace your gas boiler with a heat pump such as the Stiebel Eltron WPL17ACS that produces 9 kW of heating from 2-2.5kW of standard single-phase power input (depending on the outside air temperature and humidity, and hydronic water temperature) and is priced at $6,662 (excl GST): This heat pump is capable of producing hot water to 65 deg C which is usually hot enough for your existing radiators (depending on the size of your radiators to the size of your room, the effectiveness of your insulation and the outside ambient air temperature).

You can also reduce your heating requirement by installing energy recovery ventilation units that ventilate your room whilst recovering the inside heating or cooling energy, which open windows cannot do. Learn more about ERVs (Energy Recovery Ventilation) by clicking here.

If you require a larger heat pump, the WPL25ACS delivers 14 kilowatts of heating from 3-3.5kW of standard single-phase power input (depending on the outside air temperature and humidity, and hydronic water temperature) and is priced at $11,729 (excl GST): 

Can you power your heat pump with solar panels?

Both the WPL17ACS and WPL25ACS heat pumps can be powered by a solar system. The capacity of your solar system should be at least 5kW. Adding battery storage will make solar power available for your heat pumps at night. For heating without batteries, your heat pumps can be run during the afternoon to warm your home when you are generating solar power. The thermal mass of your home and the objects in it will act like a battery releasing heat energy when the sun goes down. For off grid applications, you can also add multiple 300 litre buffer tanks that can be heated during the day from your solar power and released at night through your hydronic system. This is another form of battery storage. 

How much would it cost?

In regard to the installation cost of changing over from a gas boiler to a heat pump connected to your existing hydronic system, it will likely involve two trades people, an electrician and a hydronics plumber, working for two days. The installtion steps would be as follow:

Step 1: The plumber will need to firstly flush out your existing hydronics system and attend to any maintenance required.

Step 2: The electrician will need to set up the electrical power supply and thermostat control system. They will then remove the old boiler, install the new heat pump and associated equipment in its place then commission the new system. Charge out rates for good trades people are approximately $90-95 per hour (+GST) so you are looking at approximately $3,000 (+GST) in labour.

Also, associated hydronic equipment, including buffer tank, hydraulic assembly, pipe work, electrical cables, electrical and plumbing fittings will cost approximately $5,000 depending on site factors.

An internet connection for your heat pump is also recommended to allow you to control your system from a smart phone and for remote engineering monitoring or assistance if required and this also extends your warranty to 5 years. So you are looking at overall an estimated installation cost of around $8,000. 

Note: These figures are strictly an estimate and indicative. Each project is to be quoted separately.

So is it worth it?

This depends on your time horizon. If this is your special home you intend to live in for the next 20 years or so, then yes, it is worth it. The capital investment is an asset that will add value to your home and with rising gas prices, your payback will improve over the years ahead. If you have to replace your gas boiler then this is the time to think about changing over to heat pump. And you will be doing something good for the environment as well!

Check out a case study on gas boiler replacement with a heat pump by clicking here.

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