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Why does the pressure keep dropping on my combi boiler?

22 Answers

Answered by Westhill Boiler Services

2nd July 2020

Westhill Boiler Services answered the question "Why does the pressure keep dropping on my combi boiler?"

There are 3 possible reasons for the pressure dropping. 1. you may have a leak somewhere on the system (boiler, radiators or pipework) 2. the pressure relief pipe may be activating (have a look at the pipe outside) 3. the expansion vessel may be flat and requires pumped back up. you can carry out a visual inspection on the system and the pipe outside, but you will require a qualified engineer to inspect the boiler.

Answered by Bells Heating & Gas

27th June 2020

Bells Heating & Gas answered the question "Why does the pressure keep dropping on my combi boiler?"

A lot of issues can cause pressure loss from a leak on the system (pipe or radiator) or components inside the boiler from passing PRV's caused by expansion vessels or pin holes in the main & plate heat exchangers. Diverter valves can also cause leaks on central heating systems. If you have a leak on your system no matter how small. always call a heating engineer to find & fix the issue quickly.

Answered by Macaulay Ferguson Ltd

11th May 2020

Macaulay Ferguson Ltd answered the question "Why does the pressure keep dropping on my combi boiler?"

There can be a few different reasons. You could have a leak on the radiator system. The expansion vessel in the boiler could be flat and the pressure relief valve may be passing water to a discharge. There may also be a leak in the boiler. Sometimes the leak is from the main heat exchanger and discharged through the condensate so is not readily identifiable.

Answered by D Steel Gas Services

4th May 2020

D Steel Gas Services answered the question "Why does the pressure keep dropping on my combi boiler?"

The most common causes of pressure loss on heating system are > A leaking on the system, ie pipes or radiators leaking. > A faulty expansion vessel and pressure relief valve. > A split heat exchanger within the boiler causing system water to disperse down condensate pipe. > A leaking diverter valve within the boiler. These are the most common faults associated with system pressure loss.

Answered by Connor's Heating Solutions

10th April 2020

Connor's Heating Solutions answered the question "Why does the pressure keep dropping on my combi boiler?"

Pressure drops are due to a leak somewhere in your boiler or heating system. It could be due to any number of things: leaking bleed valve, pipework, the boiler, flat expansion vessel etc etc. The cause needs to be address and rectified. Get an engineer to identify and repair this issue before it becomes a complete failure and causes further issues or damage.

Answered by Gas Guardian Ltd

30th March 2020

Gas Guardian Ltd answered the question "Why does the pressure keep dropping on my combi boiler?"

The pressure dropping on a combi boiler can be any (or a combination) of the below things: -Leak on the boiler or heating system -Expansion vessel charge flat, thus depleting the expansion volume of the system water when heated -Passing safety valve -Excessive gassing within the heating system which is then vented through automatic air vents causing pressure loss. (Due to sludge) Check for signs of leaks on all accessible pipework and radiators. It is highly recommended that this issue is attended to as soon as possible as failure to do so can result in excessive damage to boiler components and/or property damage.

Answered by Supaheat Ltd

5th March 2020

Supaheat Ltd answered the question "Why does the pressure keep dropping on my combi boiler?"

Losing pressure simply comes from losing the water in the system. That can be a leak on the system, in the pipes or radiators or through a cracked heat exchanger which would run out through the condense pipe and never be seen. Also an expansion vessel with no air will cause the pressure to rise with expansion and leave via the pressure reducing valve.

Answered by John Bennett Heating Limited

6th February 2020

John Bennett Heating Limited answered the question "Why does the pressure keep dropping on my combi boiler?"

This could be due to a leak on the system or in the boiler. The most common fault is the expansion vessel in your system is flat and needs re charging. Thai will result in water leaking out through the pressure relief valve. Call an engineer and he will able to asses where it is coming from.

Answered by Flo plumbing and Heating

11th January 2020

Flo plumbing and Heating answered the question "Why does the pressure keep dropping on my combi boiler?"

The most common fault is the pressure relief valve. Again this can be checked and easily fixed. The next common fault is a leaky pipe or radiator again a bit help from a engineer should solve the problem the leaky pipe or radiator is not as easily fixed if it’s not exposed and is hidden underneath the floors or hidden within the walls.

Answered by James G Martin Plumbing & Heating

8th January 2020

James G Martin Plumbing & Heating answered the question "Why does the pressure keep dropping on my combi boiler?"

There are a couple of reason for this. The usual one is that the pressure relief valve is passing and needs to be replaced. If you check the 15mm copper pipe coming out of the wall you should see if it is dripping. Alternately it could just be a slight weep on one of your radiator valves.

Answered by RW Gas Services

20th December 2019

RW Gas Services answered the question "Why does the pressure keep dropping on my combi boiler?"

This can happen for a number of reasons,the most common being a leak on the system be it on a radiator valve,the radiator or on the pipe work somewhere.Easy to spot if pipe work is accessible but hard if day buried. Sometimes it can be the boiler parts itself such as the Pressure Relief Valve,the Expansion Vessel or the Heat Exchanger. I tend to find from experience it is split 50/50 between a leak on the system or the expansion vessel

Answered by Stour Valley Plumbing

8th December 2019

Stour Valley Plumbing answered the question "Why does the pressure keep dropping on my combi boiler?"

Boilers drop pressure for a few reasons, the most obvious reason is that there is a leak on the heating system, a pipe, radiator, or valve. A system leak is easy to spot if pipework is accessible but not so easy if pipes are buried beneath solid floors. The boiler can also loose pressure if parts are faulty, Main parts to be suspicious of when it comes to pressure drop on a boiler are ; Pressure relief valve , Expansion vessel and more uncommonly main heat exchanger. The Expansion vessel and pressure relief valve are linked and are parts that are checked on a boiler service. The main heat exchanger leaking, although rare can be tested by an engineer by isolating the boiler. In my experience pressure drops on systems are equally split 50/50 between leaks on the radiator and pipework system and the expansion vessel within the boiler

Answered by Enflame Heating and Plumbing

30th November 2019

Enflame Heating and Plumbing answered the question "Why does the pressure keep dropping on my combi boiler?"

Pressure dropping in your boiler can be a number of reasons. The most common answer is that the system has a leak which could be on pipework, radiators, or boiler, also faulty parts such as the pressure relief valve or an expansion vessel will also give you the dropping pressure issues.

Answered by South Yorkshire Heating

31st October 2019

South Yorkshire Heating answered the question "Why does the pressure keep dropping on my combi boiler?"

Water is escaping somewhere. Make sure no water coming from under boiler. If so needs an engineer very quickly to save major damage to boiler. Otherwise look around the radiators and valves for any leaks. If a pressurised system take a look outside at the small copper pipe and make sure no water coming from there. Again if so you need an engineer. Could also be expansion vessel.

Answered by BPH - Blakemore Plumbing And Heating

31st October 2019

BPH - Blakemore Plumbing And Heating answered the question "Why does the pressure keep dropping on my combi boiler?"

There are a few reasons why your pressure may drop. The most common reason is that their is a leak somewhere, usually on a radiator valve or trv pin but this could be anywhere on the system. The next most common reason is that the expansion vessel in your boiler is flat or low in pressure. This could also cause the safety valve to open and 9/10 they don’t resist meaning water is constantly leaking through this valve. Another cause is that the heat exchanger had split and is leaking water through the condensate pipe. Topping it up continually isn’t the answer as you will be drawing fresh water in which isn’t good for the system, I’d suggest getting in touch with a gas safe registered engineer.

Answered by Careys Plumbing & Gas Ltd

22nd September 2019

Careys Plumbing & Gas Ltd answered the question "Why does the pressure keep dropping on my combi boiler?"

A pressure drop on your boiler means that water/air is escaping. First of all looks for signs of leaks around the system. Then check your discharge pipe outside the building for wet patches, this would show issues with the pressure vessel and/or PRV. if the system has been drained down recently it could be air escaping through the AAV in the boiler or through radiators that have been bled. Any time you bleed a radiator you must replace the air with water through your filling link.

Answered by S3 Heating and Plumbing

22nd August 2019

S3 Heating and Plumbing answered the question "Why does the pressure keep dropping on my combi boiler?"

There's a couple of things that could cause pressure dropping in your boiler. The expansion vessel could need recharging, there could be a leaking pipe/valve on your heating system or the boiler pressure relief valve could be passing. The first thing to check is if there's any wet carpet in the house near radiators which would indicate that a radiator pipe/valve is leaking. Any dripping water from the boiler prv pipe would indicate the leak is from the boiler side ie expansion vessel or prv itself. The prv pipe is normally going through the wall outside and hooked over.

Answered by iPlumbleeds.co.uk

16th August 2019

iPlumbleeds.co.uk answered the question "Why does the pressure keep dropping on my combi boiler?"

Pressure dropping on your heating system can be mainly 1 of 2 things. 1st it may be due to a leaking radiator or leaking radiator pipework. go around your heating system and check for leaks. 2nd it may be due to the pressure in your boiler going too high and dripping water out of the expansion pipe normally found on the outside of the building. The expansion pipe is made from copper and if it is dripping then you will need a engineer to come out and fix it. If you need any help call Michael from www.iplumbleeds.co.uk - 0113 80 567 83 or 07950 298097

Answered by DLM GAS Ltd

25th June 2019

DLM GAS Ltd answered the question "Why does the pressure keep dropping on my combi boiler?"

A pressure drop on a sealed heating system like that found on most (but not all) combi boilers can be down to a number of things. Occasionally this is down to a leak on the heating system. Alternatively it could be a flat or inadequately charged expansion vessel, an undersized expansion vessel, a passing pressure relief valve, a blockage or restriction, corrosion issues creating hydrogen which is venting via an auto air vent (gassing up), are non exhaustive examples of what could cause a pressure drop. DLM Gas would advise contacting a trained gas safe engineer to assess and advise on consistent pressure issues. Frequent topping up of the system water with fresh oxygenated water is very bad for your installation.

Answered by Louis Gas & Heating LTD

21st June 2019

Louis Gas & Heating LTD answered the question "Why does the pressure keep dropping on my combi boiler?"

There are many factors that can cause a pressure drop on your combination boiler. Firstly there could be a leak on the heating circuit. This would cause the pressure to drop on your combi boiler. Another could be that the expansion vessel needs recharging and this i causing the boiler to over pressurise and release pressure to outside via the pressure relief valve. Another factor could be the boiler is blocked with sludge and over pressurising and releasing pressure via the pressure relief valve. Always use a gas safe engineer to diagnose the fault on your boiler.

Answered by Jgm Gas Services

11th June 2019

Jgm Gas Services answered the question "Why does the pressure keep dropping on my combi boiler?"

If the pressure keeps dropping on your combi boiler, it means it is losing water somewhere. There are three common places to lose water: . The radiator valves. This is an easy one to check, run your hand around your radiator valves ( when turned off and with pressure in the boiler). If any of the valves are wet, then there is the problem. . The expansion vessel. The easiest way to check this is to check for water discharge from the pressure relief pipe. This is usually situated outside the property at least 0.5m below the boiler flue and it is 15mm copper. If there is any water discharging, this indicates a fault with the expansion vessel and could be the reason why the boiler pressure keeps dropping. This fault would have to be remedied by a qualified professional, as the expansion vessel is usually located inside the boiler. . The boiler. If there are any signs of water, or rust, from the boiler, this indicates that a component in the boiler could be leaking. This would require further investigation by a qualified professional. If nothing is found in the above three places, then it could be a leak on your central heating system and again, it is best checked over by a professional. Remember that anyone working on gas appliances should be 'Gas Safe Registered', so always ask to see the I.D. badge of anyone working on yours.

Answered by Priory Plumbing and Heating

10th June 2019

Priory Plumbing and Heating answered the question "Why does the pressure keep dropping on my combi boiler?"

Pressure loss could be a number of things Most common is a leak on the system check the radiator valves Pressurised system requires a safety valve off the boiler this will exit the property at the rear of boiler check this pipe to see if dripping PPHadvise you to consult a professional

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