Posted by & filed under Customer advice, Hodgson's.

Hello everyone and welcome to todays blog. I am writing today about integrity testing and the procedures/ methods in place for testing in the UK under approved Document J building regulations. Manufacturers instructions and British Standards.

First of all what is an integrity/ pressure test and why should we undertake them?

The first reason is to ensure that the chimney is not leaking dangerous fumes into other areas of the property.

Secondary reasons include the fact that the relining of a chimney is costly and may not be necessary.

Also the chimneys up draught may be badly affected by a leaking flue; it will become less efficient this can cause smoking back problems or creosote to build up on the flues linings which can lead to a chimney fire.

We have established what and why we should pressure test chimneys lets get on to how.

Smoke test type 1

Dp23 pressure testing unit used in Devon by master chimney sweep danny hodgson

Dp23 pressure tester

  • Firstly the flue is to be swept and cleared of debris and soot.
  • Roof access has to be gained to properly seal the chimney pot/ terminal this can be done with a poly bag strapped over the pot and terminal or a sponge inserted into the pot/ flue
  • Smoke test type 1 is nearly impossible to undertake on your own. 2 people are required to undertake this test properly, to safely access the roof 2 people are required for insurance purposes and to properly seal the chimney top and bottom and insert 5 or 6 smoke generating pellets into the base of the chimney is nearly impossible to do on your own.
  • The rest of the building following the chimney stack upwards has to be checked for leakage. This can be problematic if youre in a shared building.
  • If the property is over 2 stories and it cannot be accessed on ladders then a scaffolding is required, this adds to the cost of testing.
  • The test is based on the perception and experience of the user, testing chimneys integrity with smoke is biased and does not give consistent result. The type 1 smoke test involves sealing a certain volume of smoke in the chimney compartment, waiting and looking for escapes and finally juding that same amount of smoke exits the pot as was generated by the smoke pellets. This test is contentious at best and five people undertaking this test will likely give five different results.
  • Its cheap in materials. The costs involved for the chimney sweep are less as all they need sealing equipment and smoke pellets to undertake the test.

BSEN 1443 test using the DP23 or DP600

Hodgsons chimney sweeps using the latest chimney testing equipment on jobs throughout south devon

Dp 600 pressure testing unit

  • Firstly the chimney is swept and a basic smoke draw test is performed.
  • The height of the flue is measured this can be done using your chimney rods or from roof using a line and weight.
  • The flue is the then sealed at pot/ stack level. This can be done with roof access using a sponge or using an inflatable bladder inserted from the bottom.
  • The sealing elements are then inserted into the flue just above the fireplace opening along with a sensor probe and compressor hose.
  • The pressure testing unit is then attached the sensor probe and compressor hose.
  • On completion of the test the user will input the height and width of the flue into the unit, the unit will work out the allowable leakage rate and pascal rate of the flue and a pass or fail icon will be displayed there is no bias the machine does not lie.
  • A printout is then issued with test results on them.
  • The machine and its setup is very expensive and will come in at around £5000 there are also yearly calibration costs of £500 per annum.
  • The machine and the way the flue is tested is very professional and your company will look a step above the competition.
  • Its not as invasive as smoke, you do not need to access all parts of the property and most of the time you can undertake the test completely from the fireplace area, customers do not like their house filled with smoke.
  • You can do this test on your own and do not need additional help.
  • The BSEN 1443 is the only reconginsed method of testing in many european countries, smoke integrity testing is not allowed.
  • Its non bias and human error in this instance is much lower.

Know the maths

The standard for an N2 natural draught chimney allows up to 10.8 m3 of leakage per m2 of internal chimney surface of chimney per hour. So a 10 metre long chimney that is 250 mm x. 250 mm can potentially be allowed to leak 108 m3 per hour under test conditions.

Hodgsons chimney sweeps devon use pressure testing sealing sponges

Pressure testing sealing sponges

At Hodgsons Chimney Sweepswe use the dp23 testing unit for pressure testing in Devon and have done in London for many years with our London company Clean Sweep

Testimonial from London Chimney Sweeps

I have been using the DP23 pressure testing unit for about a month. Based in London, I have always had a lot of calls from customers that don’t know the history of the flue or reopening a fireplace.

I have always advised a smoke test 1, but trying to coordinate with the customer, neighbours and my own schedule during the season is a pain to say the least and sometimes not possible if the building is split into flats. The testing unit eradicates this problem, which makes it easy to arrange an appointment and judge how long it will take.

It is very easy to use and only takes a few minutes to perform the test. Before I used the unit, I was sceptical that any class 1 flues would pass, but there is an allowable amount of leakage per m3 and more flues have passed than I thought would.

A main advantage is the binary pass or fail – the customer gets a print out of the result that can’t be disputed. However, the overall cost of the unit and the maintenance is high, essential accessories are expensive and the unit must be sent back to Germany for recalibration at certain intervals – you must factor this into your pricing in addition to the sweep, roof work, time and then extra time for the explanation (if it fails).

For me, I think the unit is brilliant, but you must have the demand and cliental to justify the purchase.

You can draw your own conlusions but we will be using our machines for testing for many years to come and i hope some of you reading this will follow suit.

Thank you for reading

Danny Hodgson Master Chimney Sweep

Interested in these Services? find out more from our testing page here for Devon, Somerset, Cornwall and part of Dorset.

And for London and the Home Counties follow the link here

18 Responses to “Smoke test type 1 vs machine integrity test”

  1. RedGnome

    I have used both the DP23 and DP600 for quite a few years now. The machines itself is fantastic bit of kit, the sealing bladders not so good. It is very easy for the bladders to spring a leak or pop. If the bladders leak then you will constantly get a failed result, as all the pressure leaks out of the bladder. This could result in a lost day on site or complete product replacement if you are not aware of the bladder leaking and trying to figure out why the system isn’t passing the test. This is quite annoying as the high-tech part of the kit works and the low-tech part of the kit lets you down. Since realising this I found some high quality industrial grade sewage sealing bladders from These are quite a bit more expensive than the sealing bladders sold by Wohler, although they are way better quality and will last years to come.

    • Daniel Hodgson

      I completely agree with your comments, good to see other sweeps using top the range testing equipment. I will try the SAVAtech bladders, as you say the wohler bladders split very easily

    • Doamond Sweeps

      Thats good to know RK
      I just bought. The Dp600 and work alone usually and bladders were my option of choice. Thanks for the heads up

  2. Andy Barnes

    Very interesting, Danny. I’d be interested to know some examples of how you come to provide this service so I can estimate whether it is likely to be worth the outlay of upfront and ongoing costs in my area.

  3. bruce

    Could you provide a link to the SAVAtech bladders please? doesnt load and the eu or derivatives dont have the sewage bladders showing in their product lines.

  4. william

    Hi Daniel
    Thanks for the feed back .

    most of our chimneys are all 8 inch clay flue will the bladder be ok for them .



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