The Competition Authority has said it has received a complaint from the Association of Plumbing and Heating Contractors in relation to Bord Gáis.
The Authority says it has not begun an investigation.
However, it is now seeing if the complaint falls under competition law before deciding if there will be a probe.
The Association made the complaint because it believes the awarding of a contract by Bord Gáis to install and service boilers to one company, Sierra, means independent contractors cannot access the gas company's billing system.
However, Bord Gáis denies this.
This means customers of independent contractors have to pay for the installation of a boiler up front.
However, consumers who use Sierra can spread the cost of payment across a number of bills.
The Association also said the development has forced more consumers to use black market contractors.
The Association also claimed the Competition Authority had begun an investigation but the Authority says this is not the case.
In a statement issued by Bord Gáis, it says "since entering the boiler installation market in mid 2010, Bord Gáis Energy's Home Services has built up an approximate market share of 10%. Home Services is as an ancillary business within Bord Gáis Energy and was created in response to customer demand."
It also said "Bord Gáis Energy appointed Sierra as our managed services provider in 2009 following a thorough tender process run according to the public procurement process."
Bord Gáis says it doesn't stop APHCI members from doing this work.
"Bord Gáis Energy operates on a commercial basis and competes in this highly competitive market by offering best in class service and safety standards - as well as unique and innovative interest-free financing options to our customers. Sierra are responsible for contracting local independent contractors to work on behalf of Bord Gáis Energy and there are no barriers to APHCI members doing this work subject to being RGII compliant and meeting high quality standards," the statement added.
"The CER, through the RGI, is responsible for safety and Bord Gáis Energy operates to the very highest standards within the legal framework as set out. The company only engages with RGI compliant installers and has a robust quality audit programme," concluded the statement.
