Which Radiator to Bleed First?

Radiator about to be bled

Bleeding your radiators is a household job that should be carried out routinely as well as on an ad hoc basis, but realistically, it’s just not a task that many remember to do as often as they should.

When the term ‘bleeding’ is used in reference to radiators, it means the task of draining some of the air from the radiators. Often, excess hair becomes trapped in the radiator and needs releasing in order to allow for the optimum heading performance. But why do you bleed radiators? Put simply: it’s a maintenance task. Trapped air in a radiator can result in it having cold patches even when turned up full, taking considerably longer to heat the area around it and even not heating up at all, as it blocks the hot water from reaching all areas of the appliance. All result in sub-par heating performance, higher-costing energy bills and eventually, the requirement for a whole new radiator to be purchased as it may no longer function.

Most homes have a radiator in each medium to large sized room; or at least, each room that’s intended for really ‘living’ in (i.e. not necessarily a hallway, corridor or utility room). As such, when incorporating the job into a household routine, people often wonder which radiator to bleed first and whether or not you should bleed radiators in a certain order.

Radiators are usually bled using a ‘bleed key’ which fits into a specific ‘bleed screw’ on the top edge of the appliance. This allows for easy upward air flow without unnecessary drainage of excess liquid - although it’s not uncommon for some fluid to spill out, so ensure you have a cloth and/or small container close to mop up any watery deposits.

If you’re not sure how to bleed a radiator, haven’t done it before or need to double check you’re doing it correctly and/or safely, seek the advice of a professional plumber or heating engineer.

Should you bleed radiators in a certain order?

If you are bleeding more than one radiator at a time, ensure your central heating is fully switched off before proceeding.

In a standard house with more than one floor, the first radiator to bleed should be the radiator downstairs on the lowest floor and the furthest away from the boiler. Then, work closer toward the boiler before moving up to other floors of the home and repeating the same pattern. This allows each radiator to drain through connecting pipes nice and slowly and ensures you’re less likely to encounter any with residual heat.

In a bungalow, flat or apartment with just one floor, start by bleeding the radiator furthest away from the boiler and then work through to the closest. If bleeding just one, simply turn that radiator off individually and wait for it to cool.

If you’re unable to bleed radiators in a specific order, for whatever reason, just do what you can when you can do it. It won’t optimise the bleeding to do it any other way, but it shouldn’t cause unnecessary hindrance or damage to the process overall.

How often should you bleed radiators?

It’s easy to tell if a radiator requires a bleed in order to improve its performance, because as mentioned above, it may have stopped working to the standards you expect or give inconsistent temperature management. However, when it comes to how often you should bleed radiators, you needn’t be constrained by waiting for one to perform sub-optimally before you carry out the task.

In order to avoid radiators developing an obvious fault because of trapped air, and then bleeding it to resolve the issue, you can build a full-home radiator bleeding session into an annual routine. The best time of the year to do this and take the time to bleed every radiator in the property is during the run-up to spring or summer; when it’s likely warm enough to not require central heating all the time. If you get a particularly warm day in spring, use the opportunity when the radiators are all off to bleed all of them.

Bleeding radiators as part of annual routine maintenance can help avoid issues happening and prolong the longevity of your radiators.

It’s unlikely you have a phonebook full of heating experts, but if you ever need to chat about radiators, underfloor heating or the maintenance of either, get in touch with the Great Rads team. Our specialists are always happy to chat and offer friendly advice with no obligation to make a purchase. We just know what we’re good at – and we like to spread the knowledge!


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