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5 common mistakes when installing and selecting radiators and how not to make them

Posted by Jaga - 08 February 2016 Tips & Advice

Hi. I’m Andy Williams and I’ve been working for Jaga for the last 5 years, but I’ve been working in the HVAC industry for over 15 years so I have come across my fair share of installation mistakes.

This blog will (hopefully) help the readers from making the most common mistakes when selecting and installing their radiators for the home.

Mistake 1 – Sizing of the radiator

There is a common misconception amongst DIY’ers (and some plumbers) that you can “guess” the size (and by size I mean output rather than physical size) of a radiator based on the size of the room.But this is far from the end of this particular story.Although the size of the room is important, and can give you a guide, the other factors include, but are not limited to, the size of the windows, the construction of the windows, the construction of the walls, the flooring, the type of ceiling, what’s above and below, what’s on the other side of the walls, The temperature of the hot water circuit, and the list goes on.

It is important to get the size of the radiator correct so that the space in which the radiator is located is kept at a comfortable temperature whenever you want it.

Rule-of-thumb methods often oversize the radiator so as to make sure there are no complaints that the space stays cold, but what no-one ever tells you is that a grossly oversized radiator can cause other problems within the system.

As a practical example of the above; if you have a window that is 1.2m wide by 1m high with a high quality uPVC double glazed unit, that aspect of the room would need a radiator that had an output of 58 Watts just to overcome the loss of the window, but if the window was of a lower quality, single glazed, aluminium frame (for instance) you would need in the region of 210 Watts – nearly 4 time the amount.This is just one small aspect of the space, so you will need to calculate all aspects individually to get an accurate requirement.

As for the hot water side of things, and as with anything else, you only get out what you put in.With the increase in installations using a renewable heat source (such as a heat pump) radiator sizing is even more critical, because if they’re undersized you can’t just turn up the boiler temperature to get a bit more out of them.Nearly all suppliers in the UK work to a standard for the catalogue output (EN 442) based on a water flow temperature of 75 deg C, but heat pumps work at a much lower temperature (in the region of 45 deg C) and therefore the radiator will generally need to be larger to accommodate this unless you use something like the Jaga Play with DBE that gives an increased output without increasing the size.The increase in size might be 2 or 3 times and NOT just the 30% increase in size that many installers seem to recommend.

There are plenty of websites available that will provide a heatloss for you, but just remember that the result is only as good as the information that you put in.The more information you need to put in the better the result will be.

Mistake 2 – Orientation of the radiator

Some radiators can be installed in any orientation, but others have to be installed in a specific orientation.It is important to know whether the radiator you have selected.If you fit the radiator in the wrong orientation it can result in a reduction of output, noise from the heating system, or even in extreme cases you can end up with a radiator that doesn’t do anything other than take up wall space.This also goes for the valves.Some valves are bi-directional (meaning that water can flow through them in both directions) and others aren’t.If a non bi directional valve is fitted the wrong way round you will get a hammering noise from the valve when it is opening and closing.While this doesn’t cause any damage to the system it is very annoying.

To ensure that you don’t make this mistake check all of the information that is available for the radiators and valves.Fitting instructions are priceless for this type of information.

Mistake 3 – Balancing

When I say balancing I don’t mean standing on one leg trying to hang the radiator.Balancing is the process of setting up ALL of the radiators in the system so that they all get the required water flow.A common mistake made by installers (both professionals and DIY’ers) is to add a radiator and do nothing to the rest of the system.In 4 out of 5 domestic installations this wouldn’t be a problem, but on that one occasion that it is a problem, it can be a big problem.

Basically water is lazy and it will take the easiest possible way to get back to the boiler. Towel rails are probably the biggest culprits when it comes to causing balancing problems.Because the towel rail and valves are so open they put up very little resistance to the water.This makes a very easy path for the water to circulate through, and therefore stopping the water from travelling to the other radiators.If you can imagine that you are travelling from one town to the next.Generally the quickest way is via the motorway and this is the way you would go. But if there was a hold up on the motorway then the A-roads will be just as quick, and if there is a bigger hold up on the motorway and a small hold up on the a-roads, then the country roads will be just as quick.The same principle applies to balancing the heating system.All the radiators, valve and associated pipework need to have the same resistance (hold up) so that there is no way of going quicker by taking a short cut.

This is a very common mistake when adding radiators to the system, such as an extension or loft conversion.It can be easily overcome by balancing the radiators.This is done by slightly closing some of the valves to force the water to take a different path.

Mistake 4 – Pipe sizes

There is a rule-of-thumb method of sizing pipework for heating systems based on the number of radiators.But every radiator is different.In much the same way that a shopping basket is suitable for 5 bags of crisps, it is far from suitable for 5 bags of coal.It goes without saying that a 1kW radiator is smaller than a 4kW radiator so if you had 10 number 4kW radiators, then this has a much higher requirement from the water circuit than 10 number 1kW radiators.If your pipework is the wrong size then you will get high pressure drops in the system causing strain on the pump, and in some instances you might even get a whistling noise in the pipes when the system is running.Generally the rule-of-thumb methods are based on 1.5kW radiators so a 4kW radiator is worth approx. 2.5 radiators when using the rule-of-thumb.As long as you bear this in mind when you are putting in the pipework then you should be OK.The alternative is to calculate the pipe sizes correctly but this will probably involve a lot of extra cost and time if you don’t know how to do it yourself.

Mistake 5 – Positioning

Although the position of a radiator is generally accepted as a decorative decision, there is a practical consideration that many people overlook.In nearly every property domestic property I’ve ever been into the radiators are located under the windows.This is mainly because the window has already “ruined” that particular wall space so why not put the radiator there as well.And while that is acceptable for the appearance it is not always the best position for the functionality of radiator, especially if the radiator is then “hidden” by furniture or curtains.If the radiator is of the steel panel type, then any obstruction in front of the radiator will stop the heat from entering the room.If you are using a convector radiator, such as the Jaga Knockonwood, then it is not an issue to put something in front of them.Convectors rely on air circulation, so a gap is required underneath to allow for this airflow, whereas a radiation type radiator relies on the heat radiating into the space, and therefore anything in the way will stop the radiation.

When selecting the style of radiator it is important to consider what the room is going to be used for and what other furniture is going to be in the room.This might mean that the radiator you want needs to be re-located.

So if you can avoid all these mistakes, then you should be OK. Good Luck

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