Heatrae Sadia Multipoint: Faults, Parts and Repairs

What a Multipoint is, and what it is not

Heatrae Sadia is the manufacturer behind Megaflo, and alongside its full size cylinders it makes small water heaters for places a cylinder cannot reach easily: an office kitchen, a cloakroom basin, a utility room, or a flat where the main hot water is a long pipe run away. The Multipoint is one of those. It is a compact insulated tank with an electric element inside, fed straight from the cold mains, and it delivers hot water at mains pressure to an ordinary tap.

The name causes confusion. A gas multipoint is a completely different appliance: a wall mounted gas water heater, often an old Ascot or similar, that heats water instantly as it flows. If yours has a flue, a pilot light or a gas pipe, it is not a Heatrae Sadia Multipoint, and our guide to a gas multipoint water heater not working covers that kind instead.

It is also different from the vented, or open outlet, heaters that sit under many sinks. Those are not under pressure and need a special three pipe tap. The Multipoint is unvented, which is why it works with a normal tap and why it has a small group of valves on the pipe going into it. Our overview of Heatrae Sadia cylinders explained covers the rest of the range if you are unsure which appliance you are looking at.

How to identify your model

Look for the data label on the front or side of the unit. It gives the model name, the capacity in litres, the element rating and usually a serial number that dates the heater. Take a clear photo of it before you do anything else, because it is the first thing any engineer or parts supplier will ask for.

Then look at the cold pipe going in. On an unvented heater you should see some or all of the following.

• A pressure reducing valve, which drops mains pressure to what the heater is designed for.
• A check valve, which stops hot water pushing back into the cold main.
• An expansion relief valve, which opens if pressure in the heater climbs too high.
• A small expansion vessel, a round or cylindrical metal tank, on many installations.
• A discharge pipe running from the relief valves to a tundish or a visible drain point.

Other Heatrae Sadia names, such as Streamline, Express and Supreme, turn up on small heaters in the same places. Some are unvented and some are not. The label and the valves on the inlet tell you which you have, not the name alone.

No hot water from a Multipoint

Start with the electrics, because it is free to check and it is the most common cause. A Multipoint is normally wired to a fused spur, a switch with a small fuse and often a red neon, near the heater or in the cupboard. Check it is switched on and the neon is lit, and check nothing has tripped in the consumer unit.

If there is power and still no heat, the overheat cut out has probably tripped. Every heater of this kind has a safety cut out that switches the element off if the water gets far too hot, and on most models it has a manual reset under the cover. It is designed to trip rarely. If it has tripped, something caused it: a thermostat that stuck on, scale around the sensor, or an element running hot. Do not take the cover off with the power on, and if it trips a second time, leave it off.

If neither is the cause, the element or the thermostat has usually failed. Both are tested with a meter with the power isolated, and both are replaceable parts on a heater that is otherwise sound. A heater that trips the RCD as soon as it is switched on almost always has an element that has broken down to earth. The same fault on a bigger scale is covered in our guide for when an immersion heater keeps tripping.

Water dripping from the relief valve or discharge pipe

This is the fault that worries people most, and it is the one that most needs a proper diagnosis. Water heaters expand the water inside them every time they heat up. On an unvented heater that expansion has to go somewhere, which is the job of the expansion vessel. When the vessel loses its air charge, or its internal membrane fails, the expansion has nowhere to go, pressure rises each heating cycle and the expansion relief valve lets a little water out. The pattern is a drip or a trickle that happens while the heater is warming up, then stops.

A drip that never stops, even when the heater is cold, points somewhere else: a pressure reducing valve that is no longer holding mains pressure back, or a relief valve with a scrap of scale or debris stuck on its seat. Hot water or steam from the discharge is a different matter again. It means the temperature controls have failed and the last line of defence is working. Switch the heater off at the spur and call an engineer.

The same logic applies to full size cylinders, so our guides to a pressure relief valve leaking and a tundish dripping are worth reading for the detail. On a Multipoint the parts are smaller and cheaper, but they must be the right parts at the right settings.

Never cap, plug or tie off a dripping relief valve or discharge pipe. It is the part that stops a pressurised heater from failing dangerously. The drip is the symptom, not the fault.

Low flow, lukewarm water and scale

A small heater holds a small amount of water, so first check it was sized for what you are asking of it. A 10 litre unit on a handbasin is fine. The same unit on a kitchen sink being filled for washing up will run out, and that is not a fault.

If flow has dropped over time, the strainer in the inlet group is the usual suspect. It catches debris from the mains and slowly clogs, particularly after water main work in the street. If the water is only lukewarm, scale on the element is more likely. The element in a small heater sits in a small volume of water that is heated and reheated all day, and in hard water it scales quickly. Our guide to hard water and hot water cylinders in London explains what that does to any water heater, large or small.

Does a Multipoint need a G3 qualified engineer?

Under the Building Regulations, the Part G3 rules on unvented hot water apply to storage systems of more than 15 litres. A 10 or 15 litre Multipoint falls below that, which is why these heaters are often fitted without the notification and certificate that a full size cylinder needs.

That does not make the safety devices optional or the work trivial. The heater is still a sealed vessel on mains pressure with an electric element in it, sitting in a cupboard next to water and often next to food. The valves have to be set and matched to the heater, the discharge has to go somewhere safe and visible, and the electrics have to be right. In practice, the engineers best placed to work on a Multipoint are the ones who handle unvented cylinder repair every day. Our page on the G3 qualified engineer service explains what that qualification covers on the larger systems.

Repair or replace?

Most Multipoint faults are repairable. Elements, thermostats, cut outs, the valves in the inlet group and expansion vessels are all separate parts, and replacing one restores a heater with years left in it. Heatrae Sadia models have been around long enough that parts for common versions are generally available, although very old units can be harder to source, which is another reason to photograph the label before anyone orders anything.

Replacement makes sense when the tank itself is leaking, when the unit is old and more than one major part has gone, or when the heater was undersized for the job from the start. If you are replacing it anyway, it is worth asking whether a small heater is still the right answer, or whether the outlet could be served from the main hot water. Our comparison of an instant water heater or hot water cylinder sets out those options.

Getting a Multipoint looked at

If the spur is on and the heater is still cold, if the cut out trips again after one reset, or if the discharge pipe is dripping, call us or send an enquiry with a photo of the data label and the valves on the cold pipe. That photo usually tells us which part is likely to have failed before we arrive, so the right one is on the van. Our rate is set out on the pricing page and agreed before we attend. If you have hot water or steam coming from the discharge, switch the heater off at the spur first and then call.