Gas Safe Engineer Shares Top Boiler Advice for Landlords

A dodgy boiler is the most common problem that UK tenants face. In fact, nearly a third of tenants have experienced a lack of hot water or central heating during their tenancy.

There’s a great chance boiler problems have already cost you a lot of time and money – or will do in the near future. Here’s your chance to prevent heating problems with professional advice from a registered Gas Safe engineer.

1. Topping up a Boiler Isn’t a Fix

One of the most common boiler problems we encounter is a lack, or loss, of pressure.

Naturally, homeowners and tenants feel topping up the boiler via the filling loop is a nice fix to the problem.  90% of the time, however, pressure loss is due to a leak. And topping up your boiler isn’t going to fix that leak.

If you’re unfortunate enough to have a leak under your flooring that is not visible yet,  then the long-term effects are not going to be pretty. It shouldn’t be ignored by simply topping up.

If your system has a leak, and you top up the boiler, you are diluting the inhibitor. Reducing the current level of protection on the system. Some manufacturers’ warranties become void if the central heating inhibitor levels are found to be too low, so keeping on top of this issue is definitely in a landlord’s best interests!

Engineer’s Advice:

  • Check pipework, radiator valves and towel rails for visible leaks, and find your culprit.
  • If you find a leak, make sure it’s bone dry. Run the heating system, and then come back and check it.
  • Tightening up radiator valves and bleed caps is sometimes enough to stop leaks.

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2. Limescale Is a Boiler Killer

Hard water isn’t just bad for your skin. It’s bad for your boiler, too.

This handy graphic shows the hard water areas in the UK. These are areas where the water has excess minerals and particles in it. Over time, this hard water produces a build-up of limescale.

Limescale can build up in the heating system, blocking pipes and even expensive parts like the heat exchanger. If you can see that you are in an area of hard water, limescale is something you need to be very aware of.

Engineer’s Advice:

  • Next time you have an engineer out, ask if they can install a scale reducer.
  • It doesn’t hurt to add a scale reducer on any system, but is much more important in areas that are supplied medium-hard water.

3. Sludge is a Major Issue

Inhibitor does a great job of breaking down materials and sludge in your system. But where does it go? If you have a microbore system (8mm/10mm pipe) sludge can sometimes get lodged in pipework and valves, and even a power flush won’t get rid of it.

Engineer’s Advice

  • Almost every system we fit has a magnetic system filter included in the boiler installation price. And we suggest fitting them on systems that didn’t have one installed prior. Ask to have one installed.
  • Here is a quick video from MagnaClean showing what these filters do to the water flowing around your central heating system.
  • Important Note – Make sure you get the engineer that services your boiler to clean out the system filter with each service.

4. Power Flushing Is Rarely the Best Option

I can tell you right now, power flushing and old heating systems is rarely a good combination.

Over time, soldered joints (elbows, tees, couplers) can become weak. Dosing a system with powerful chemicals and then putting immense pressure on them is asking for one thing: leaks.

Sometimes a power flush won’t fix the problem. Why?

Pipework might be microbore (8mm and 10mm pipe). A power flush rarely fixes “sludge” related systems in this case. Another reason a power flush might not fix your problem is that the pipework may be in-correctly routed. I had this issue on a maisonette I purchased. We had to re-route most the pipe-work to all the radiators.

Engineer’s Advice

  • Power flushing is expensive (I’ve written an in-depth guide here). Make sure you get a report of the engineer’s findings before going ahead.
  • Remember, newer radiators can be up to 50% more efficient. With power flushing costs weighing in at around 40% of actual radiator installation (including parts), it makes much more sense to replace them in most cases – especially on systems that are over ten years old.

If you think your boiler is in need of a good once over, why not book in one of our Gas Safe engineers for a servicing? Just click here.


Luke is a Gas Safe registered engineer with over 10 years’ experience. He has worked on both commercial and residential projects, and a range of new builds. He writes over at his heating blog a few times a month.

One Reply to “Gas Safe Engineer Shares Top Boiler Advice for Landlords”

  1. I’ve had two oil boilers wrecked by tenants who tip the oil tanks and only top up with drums (5gall)so the burners are damaged My leases state that doing the above is a no no. I service boilers once a year .Tennant rights what about landlord’s rights the way I feel at the moment as my properts go empty I’ll board them and leave them empty with house prices rising it will be win win

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