Is a heat pump water heater right for your HDB flat?

How a heat pump model differs

An instant heater warms water as it flows through and has no tank. A heat pump water heater uses its own heat pump to warm the water, then stores it in a tank until you need it. Plan for the tank's size and for its weight when full, and ask the maker what kind of wall or floor it needs.

The National Environment Agency (NEA) regulates water heaters for household use, and its circular on regulated goods shows that these include heat pump water heaters of up to 6 kW and up to 500 litres.

If you are weighing up a heat pump vs storage water heater, running costs will come up next. The instant vs storage running cost comparison sets out how the two common heater types compare. Start there, and ask the maker for the figures behind any model you shortlist.

The Energy Label

Water heaters sold in Singapore, including heat pump models, must meet NEA's minimum energy efficiency standard and carry the Energy Label. NEA's Energy Label page lists water heaters among the appliances that carry the label, and a water heater label shows the storage volume in litres.

Before you look at brochures or sales claims, read the heat pump water heater Energy Label on each model you shortlist. Note its energy rating and its storage volume, then compare the models on those same points.

To estimate what a model may cost to run, try the water heater running cost calculator.

Heat pump water heater HDB checks: power and the main switch

HDB's limits depend on your flat's main switch rating. Its renovation guidelines for electrical works say that for flats provided with a 30amps main switch, "Consumption of individual appliance should not exceed 3kw for instantaneous water heater, washing machine with heater, electric oven, oven, and cooker unit" and "Consumption of appliance should not exceed 1.5kw for storage water heater". The 1.5kw figure is HDB's limit for storage water heaters, so ask the seller or HDB how it applies to your model.

For 40amps flats and flats upgraded under the Main Upgrading Programme (MUP) or Home Improvement Programme (HIP), the same HDB page says: "No restriction on the number of appliances installed but subject to the limitation of existing main switch rating and the rating of appliances not exceeding 15amps power point".

Not sure which main switch your flat has? It sits in your distribution board (DB box), and the guide to reading your DB box shows where to find the rating.

For the power connection, see the Energy Market Authority (EMA) page on engaging Licensed Electrical Workers (LEWs). EMA says electrical work in an HDB flat needs a Licensed Electrician, the class of LEW approved for loads of up to 45kVA.

Space, airflow and the pipework

Choose the spot before you choose the model. Check that the place you have in mind has:

• floor or wall space indoors that can take the weight of a full tank
• room for air to move around the unit, with the clear space the maker asks for
• a route for the hot and cold water pipes
• a power point within reach, or a plan for one (see the power section above)

The water pipes need the right person too. PUB's Plumbing Works page lists simple jobs, such as the pipe between a stop valve and an instantaneous water heater. Pipework for a storage water heater is not on that list, so it is work for a PUB Licensed Plumber. A heat pump model also keeps its water in a tank, so ask the company you book who will do the pipework.

Ask too whether the job includes removing your old heater. The water heater installation steps guide sets out the usual order of work.

Questions to ask before you buy

Whichever heat pump water heater Singapore shops show you, ask these questions before you pay:

• Does the tank size suit your household? Think about how many people shower and when. The water heater size calculator helps you match a size to your home.
• Where will it sit, and how will air reach it? Check the indoor space, the full-tank weight and the clearance the maker asks for.
• What does the label say? Note the energy rating and the storage volume on the Energy Label.
• Does your main switch rating allow it? Compare the model's power rating with the limits in the power section above.
• Who connects the pipes and the power? Ask who will do each part, and check they hold the licences described above.
• What does the warranty cover? Ask what is covered, for how long and who to call if the unit leaks or stops heating.

Keep the water heater buying checklist open as you compare models. Price depends on the model and the job, so ask each company what its quote includes.

Questions