CO/Fire Dangers from Unvented Heaters

jp_2

I'd trust your data!

Unknown

Unvented Heaters & CO

This is some information sent to me by way of my area on www.oiltechtalk.com from a gentleman in England concerning unvented heaters. It has been my experience so far that no known incidents has occurred with these units here in the USA. You will however note when going over **** Gambles attached postings that they have had some incidents in the United Kingdom. In case you are not aware of it the allowed Carbon Monoxide level by ANSI Standard on these units is 200 PPM. I personally strive to see levels well below 25 PPM.

I am curious to know if any of you know of any similar incidents?

Hi Timmie

There has been a recent tragic CO related death over here in UKGB.

See: -
http://www.southwalesargus.co.uk/display.var.927059.0.gas_fitter_admits_girls_manslaughter.php

Gas installers here must be CORGI registered (http://www.corgi-group.com/) and to have passed competence assessments for all the types of appliance they install or service (both domestic and commercial).
We have to attend retraining and reassessment every 5 years and notify CORGI of every gas installation we do. Our gas work is inspected at random during the five years, but a certificate is sent from CORGI (the gas installers regulating body) after notification to the end user confirming that the installation was carried out by a competent person, its called a "Declaration of Gas Safety".
An anomaly exists over here, whereby a member of the public can legally buy a flueless gas fire at a DIY store.

It seems that there wasn't oxygen deficiency in the room so the (oxi-pilot) pilot burner did not extinguish, but carbon monoxide was produced due to too high a gas pressure causing the catalytic plate to soot up.
The full facts are yet to come out and UK gas installers are concerned that they do.
I wondered what the experience of these flueless catalytic gas fires is in the USA.
For example do you have pressure regulators fitted in the appliance to protect against say a malfunction of the main meter governor?
Most UK chimney flued gas fires only have screw to throttle the governed gas supply, which for natural gas here is 20mb (8 inches water gauge), down to the appliance operating pressure.

Any help appreciated.
Best regards ****

Hi ****,

Yes we have unvented gas burners here in the USA. I am not a big fan of these heaters as I think they are dangerous. Supposedly there have been no incidents of Carbon Monoxide poisoning from any here in the USA. They now use a quick drop out thermocouple instead of the Oxygen Depletion Safety Pilot that was used on older models.

I have done some testing when I was with the gas utility on these and found I could make CO without the ODS shutting off the system. The ODS was supposed to work if the oxygen level dropped below 18%.

I strongly recommend the use of a CO Detector when using one of these heaters. They are also only to be used as a supplemental heating system and should be operated with a window open. Now why would I want to open a window when I am trying to heat a room?

I will post some more on this subject when my computer is back up.

From **** Gamble

Your comments are appreciated Tim and reinforce some of our thoughts on this type of product.
I believe the manufacturer's installation instructions have recently been amended and now include flue gas analysis.

I posted on Gas-News "The flue less Fire installation instructions make interesting reading. See http://www.focalpointfires.co.uk/page5.html

a) An electronic combustion analyzer is required.

i) To test the fire box for leakage of Products Of Combustion. All POC's must pass through the catalytic converter and not bypass it due to fire box leakage.

ii) Combustion test after 15minutes on high. Maximum CO/CO2 ratio must not exceed 0.0015.

iii) The life of the catalytic converter is 11,000 hours or 10 years normal use, needs testing and replacing as necessary.

b) 100 square centimeters of permanent ventilation (50cm2 at high level and 50cm2 at low level) required.

c) Minimum room size 30 square meters and fire not to be located in a sleeping area or bathroom.

d) Quote "8.3 the fire is factory set to achieve these pressures and any significant variation could indicate a supply problem."


What I feel could be most significant, is that I don't believe that there is a gas pressure governor (diaphragm type regulator) fitted on this appliance as the MI refers to the Main Burner Flow Restrictor. (This fact obviously needs confirming)

The majority of flued (vented) or balanced flued boilers over here have a multifunction gas valve containing an integral governor.
This is a flueless appliance so if no governor, what happens if there is a malfunction of the main meter governor and supply pressure increases???

Sales literature implies that this product is inherently safe (with provisos).
Safe enough to be sold in DIY outlets, with the advice that it must be installed by a CORGI registered gas installer. As we say 'Yeh Right!' meaning it 'aint gonna happen.

Gas Installers over here are deeply concerned

1) For the health and safety of the general public (our customers) and

2) No one wants to incur the liability of installing something that is potentially dangerous.

I am particularly interested in the quick drop thermocouples could you let us have details of some makers and part numbers?
In case there is a difference in terminology this is an O.D.S. www.focalpointfires.plc.uk/ods/

Once again thanks for your input.
Best regards **** Gamble

1) Posted on www.gas-news.co.uk
By Paul Robin Lerner (Georgeorwell) on Tuesday, September 26, 2006 - 04:35 pm: Edit Post

"Someone has spoken to Scott Stuart's solicitor today.

The fire in question was Excelsior flueless and not Plasma but does have a catalytic converter.

1800 of these were subject to recall.

The fire has been significantly changed from the original design.

It appears that this fire was fitted approximately 5 months prior to the tragedy. It was 12 months after the young girls death that Mr. Stuart was charged.

The burner pressure on these fires is 7mbar (2.8 inches water gauge), from information given to us yesterday 2mbar (0.8" wg) above this and you get flame impingement and the catalytic converter soots up".

2) Posted on www.gas-news.co.uk
By Chris Hutt (Chrishutt) on Tuesday, September 26, 2006 - 09:28 pm: Edit Post

Here's a link to the Excelsior fire.
http://www.focalpointfires.plc.uk/centurion/
I've extracted the following text from that link. It seems rather ambiguous to me (unless you take it literally, in which case it's clearly wrong!).
"The Excelsior 30 must not be installed in a room or space smaller than 30m³ with an openable window and purpose provided ventilation of at least 100cm²"

The Focalpoint fires site is also a bit confusing because some Excelsiors are flued appliances, which could conceivably lead to the wrong appliance being installed!

And guess who approved (CE mark?) these fires? British Gas Technology!

Also check out this page of the site - useful background.

http://www.focalpointfires.plc.uk/facts/

This is an extract from that page - "Safety
The safety record of the flueless appliance is second to none. In the 20 years of consumer experience in U.S.A. there is not one recorded fatality attributable to emissions associated with the use of a flueless gas-heating appliance. By contrast, in the 3 year period 1995 - 1998 there were 89 deaths and 833 cases of carbon monoxide poisoning in the U.K. alone as a result of use of flued gas appliances."

(Also posted on argi.org.uk)

Posted after my visit with John Brooks a CORGI member from the UK who visited with me in Warren, RI at my training center while he was visiting here in the USA.

My visit with John Brooks from Croydon Calorific this past Wednesday October 4th at my training center was a very enjoyable time. We had a nice dinner at the local waterfront restaurant (Wharf Tavern) with his wife. My wife was ill and not able to attend.

We had some interesting discussion about many of the same obstacles being faced here in the USA and also in England. I look forward to more communication with John and also with **** Gamble.

To the best of my knowledge there have not been any incidents (Carbon Monoxide) here is the USA from unvented space heaters.

I must however report that while I was at the gas utility and responsible for testing any equipment sold on our lines we did have some testing that showed a potential for problems.

We slightly over fired a unit and found we could produce over 400 to 500 PPM in a tight room with very little air change. It took over 2 hours before the ODS pilot went out. This was not considered a problem as such due to the fact that the unit was overfired and they
Were not tested back then as related to overfiring. I have had other incidents in testing when the ODS did not shut down with levels of O2 in the room at less than 18% but air still being fed in at the pilot level. So the fact is that under certain conditions there can be a dangerous condition created.

I am going to post all of this info over on the wall and at HVACProtech.com.

jp_2

question for you tim

awhile back you were talking to someone about these units, how the O2 depletion sensor operated. can the O2 drop to the 18% range and the unit still produce relativily low CO?

or as the O2 starts going below 20% the CO start rising?

Is there data about this?

Unknown

The O2 being measured

is the room O2. The answer is that room O2 can drop and not affect CO as typically the O2 is being measured at mid point in the room. The problem is that my testing (keep in mind I am not a lisensed testing lab)shows that CO can be being produced even though O2 levels are going below 18% and the ODS has not shut the unit off. I was able to create this on several different units from different manufacturers.

This will definetely be occuring if the heater is slightly overfired.Most of these heaters are 40,000 BTU's or under.

I do not have data that is recorded anywhere. The only data that would be available would come from AGA or UL depending on who did the required testing for certification.

Hope that helps.