Simple explanations for plumbing problems

Filling loop left open

After use the valves on the filling loop should be closed, the metal braided filling loop removed and the valves capped.  The majority of people don’t do this so there is always a chance that the valves can be opened accidentally or be faulty.  This can allow too much pressure to develop in the system which may cause the metal pipe near the boiler to overflow.

The first step is to turn the taps so they are in the off position. If its a round tap turn it clockwise.  If it has a lever turn it so that is not in line and at 90 degrees with the body of the valve.  If it has been accidentally turned on you will hear the water flowing and hear the flow stop when you turn the valve to the correct position.

The filling loop below is open


The filling loop below is closed


It doesn’t need to be as pronounced as this to cause the pressure to go up, even slightly open is enough.

To fix this you need to turn both valves (or one if you only have one) off. This should make the metal pipe outside stop overflowing.

The metal overflow pipe should only overflow if the pressure is above 3. So when the pressure goes back down below 3 the water should stop.

If it doesn’t then you might need a new safety valve as they are notorious for not resealing after they have opened. This is a job for a gas safe engineer not DIY.

Leave a comment »

Why boiler servicing is important.

I went today to a tenant that thought his boiler was working fine. He was so sure it was fine that he’d arranged to meet his parents when I left.

The boiler looked ok from the outside but inside it was very different.

The burner seal had turned from flexible silicone to crumbling dust.

This meant that when the boiler was firing fumes and steam were leaking into the inner case. It’s easy to see the heat marks and corrosion at the top of the round burner door.

If this is left for any length of time serious damage can be done. I’ve seen cables melted by the heat and electrical components short circuited by the steam.

When I removed the burner the top part of the silicone seal disintegrated completely. Luckily for the tenant I keep a spare seal on my van so I soon had it replaced.

With the new seal in place and the burner refitted I could continue the service. From that point I could agree with the tenant that everything was working fine.

Leave a comment »

Changing a leaking stop tap

This stop tap had been leaking a little bit for a very long time. Not enough for the customer to consider it an emergency. But enough for it to cause an unpleasant smell under the kitchen sink.

The customer was in the habit of turning their water off when they went on holiday. I think that’s a good habit to get into but this had worn the gland that seals the tap handle.

It’s possible to repair this by stuffing some PTFE tape into the gland. I never think of this as a long term measure so I always change the whole valve. You can find a stop tap on this link.

After turning the water off at the stop cock outside in the footpath I turned on the taps in the property to drain the pressure then turned them all off. This removes the pressure in the system but helps to hold the water in the pipes.

The tap was in a awkward position so I turned it off, loosened the bottom connection then put the whole tap in a bin liner with the valve still closed. When I opened the tap there was a gush of water but it was all safely contained in the bag rather than going under the kitchen units.

Once the water stops running it’s a simple job to remove then refit the stop tap. I always like to wrap a bit of PTFE tape around the olives for extra peace of mind.

Turn off the stop tap then turn on the external stop tap. Check for leaks, turn on the stop tap, check for leaks. Leave it for 5-10 minutes check for leaks.

Leave a comment »

When bleeding a radiator doesn’t work.

This customer had a radiator that he couldn’t bleed but also wouldn’t heat up past half way.

He had already figured out the price for replacing his broken radiator when I arrived.

Luckily for him I’ve seen this many times and it’s easy to diagnose where the fault is.

When you bleed a radiator the air has to come out of a opening inside the bleed point. On this particular type of bleed point (myson radiators) the opening is very small. As it’s so small it very easily gets blocked up by sludge or dirt in the system.

Even when the bleed pin was completely removed there was still no air or water coming out.

However when I turned the whole bleed point fitting air (followed by water) did come out. Proving that there was no fault with the radiator itself.

The simple solution to this problem is to poke a fine needle into the hole. This breaks the dirt crust and allows the water and air to come out. First you must turn off the valves to the radiator and put a tray and some towels under to catch any spilt water.

As soon as you break the dirt the air will come out (quite fast). The idea is to get the screw back into the fitting as fast as you can (without cross threading it) so no water is spilt. The time you have to do this depends on how much air is in the radiator and how much pressure is in the system.

The drip tray and towels are your very best friend if you can’t work quick enough.

Leave a comment »

When a leaking radiator drops pressure.

The pressure on the customers boiler had been gradually dropping over several months. As the drop was so slow it couldn’t be a massive leak. She showed me a radiator that had a rusty mark around one of the plugs at the top. This was more than likely the culprit.

Although there was no drip of water or any marks on the floor underneath it did feel wet to touch. Over several months this is enough to drop the pressure so it has to be changed.

The process of changing this plug is pretty simple. You can find a replacement plug on this link.

Turn off the valves, bleed the pressure out of the isolated radiator then take the plug out.

The valves were both lock shield types so I closed them with my tiny pump pliers.

Then I bled the excess pressure from the bleed point catching the dirty water in some blue roll.

When the water stops coming from the bleed point you can be pretty confident the pressure is gone.

Next unwind the plug from the radiator. I like to use pump pliers as they give a better grip. However they chew the fittings up. If they are on show or decorative you need to be more careful.

Even though the pressure is gone a fair amount of water still comes out when the plug is removed. Have plenty of blue roll and a tray ready to catch it. Especially with light coloured carpets.

When the plug is removed clean the inside of the threads to remove any old sealant and dirt. Then refit the replacement plug. Use a flat spanner (I use an adjustable) to refit it. This saves the chrome from being chewed up.

Reopen the valves and check for leaks. If you have a pressurised system check the pressure gauge. Top up if necessary.

Leave a comment »

OO Fault on an Ideal Logic

Although this isn’t really a true fault it’s still a problem I’ve been requested to fix.

OO is displayed on the front of an Ideal Logic boiler when there is no demand. For a combi boiler that is:

  • Room thermostat set too low
  • Heating timer turned off
  • No hot water taps open.

To cure this fault (if there is no other fault) you will need to create a demand. Try one of the following: turn a tap on, turn your thermostat up or switch on the heating. As soon as there is a demand the OO should change to a temperature reading and either a radiator or tap symbol.

If you’ve got a demand such as a tap running or the heating is turned on and the OO is still displayed then there may be a fault with the boiler or the controls.

The most common reason is a thermostat that is turned down a little bit below the room temperature. Try turning the stat fully up. Try turning a hot tap on if the OO still won’t change. A tap symbol and a temperature should be displayed.

If this doesn’t work you’ll need to get a gas engineer or electrician to check you boiler or controls.

Leave a comment »

E50 fault Baxi or Potterton boiler

An E50 fault on a Baxi or Potterton boiler is a sign that the hot water sensor is faulty.

The hot water sensor is screwed into the left hand manifold. It sits it the stream of the mains water so it needs to be sealed using a washer.

To rectify this fault the sensor and seal should be replaced by a gas safe registered engineer.

Leave a comment »

Potterton promax low pressure E119 fault

The customer is getting an E119 fault everyday. They top up the pressure in the morning and it’s gone by the afternoon.

This is a classic expansion vessel fault.

The expansion vessel is a tank with an air bubble inside. (Red tank on the left). It uses this air bubble to keep the pressure in the system steady.

Over time (or if there is a fault) the air bubble leaks away and pressure in the system is no longer controlled.

When the system heats up the pressure isn’t controlled so goes too high. It is then released by the safety valve. This lowers the pressure causing the E119 fault.

The air bubble is reinstated in the tank using a bike pump.

When the bubble is back in the expansion vessel the pressure should stay under 2.5bar when hot.

Leave a comment »

Why should I bother getting my boiler serviced?

Modern boilers are designed to be safe. All the dangerous bits are sealed up inside an air tight case. This means if anything does go wrong inside the boiler the carbon monoxide doesn’t tend to leak out into your house.

It also means that if things are going wrong you may not know about it until it’s gone very wrong.

This boiler I serviced was a potterton promax combi (a very good boiler incidentally). The customer was happy with how it was working, never had to reset it, all working very well.

When I took the cover off the marks of leaking heat and fumes were obvious immediately. The rubber sealing gasket for the burner had disintegrated and was no longer sealing the heat exchanger.

Along the top edge of the burner door you can see wispy white marks where the fumes and heat have been leaking. In the bottom of the case was white powder from the metals corroding. When I took the burner out it was obvious that the silicone rubber seal had failed.

Luckily this had been caught in time at the yearly service so no harm had been done.

The new silicone rubber seal costs a few quid. Fitting it takes hardly any time and because it’s in the middle of a service all the safety checks have to be done anyway so no extra work.

I’ve come across this seal failing a few times. Mostly caught early. Two were not caught early.

The first one had the fumes and hot gasses leaking for a long time which burned through the wiring and spark generator above the heat exchanger. This eventually put the boiler off. A costly job replacing the parts.

The second one was left for even longer. It eventually melted the wiring , spark generator and burnt though the plastic body of the main heat exchanger. Parts cost went into the hundreds and labour added even more hundreds.

The moral of the story is that a stitch in time saves nine. Get your boiler checked once a year. It might save you a lot of money and trouble.

Leave a comment »

My water is too hot can i make it cooler

The standard answer to this is no, hot water is supposed to be hot.

Lukewarm water is an amazing breeding ground for all sorts of unpleasant microbes such as legionnaires disease. Legionnaires disease doesn’t survive above 60ºC so keeping the hot water temperature above this ensures the water is safe.

The second reason to keep your hot water hot is the storage cylinder is relatively small compared to the amount of water you need. The volume of the hot water storage cylinder is probably just enough to fill a bath. But if you use half the water from the tank and dilute it with cold from the main you could get two baths from the same small tank.  This would save time heating the water again before use.

Mixing valves can be added to hot water systems to reduce the temperature of the water at the taps. This allows the water to be kept at a high temperature (above 60ºC) in the tank but still delivered to the taps without the risk of scalding.

Leave a comment »