Kulwinder Bola, owner of the Royal Renaissance Hotel in Skegness, was also found guilty failing to appoint a planning supervisor for the works, which were carried out in 2006.
The court heard Mr Bola had being undertaking a refurbishment at the hotel, but had failed to employ a registered gas fitter to install the pipework and gas catering appliances.
HSE inspector Judith McNulty-Green said: "When the inspector visited the hotel a number of items were found to be immediately dangerous, including the gas supply to appliances.
"Four appliances were fitted with flues and required extraction but no extraction system was operational. Due to the danger of carbon monoxide, those appliances were disconnected from the gas supply and a prohibition notice was served banning their use.
"However, the defendant told his chefs they could use the banned equipment.
"HSE takes very seriously breaches of notices. Ignoring the ban was extremely dangerous and posed a serious risk to employees at the hotel."
Mr Bola received a 12 week custodial sentence, suspended for 1 year.
He was also ordered to carry out 200 hours of community service within the year and to pay the full court costs of £20,623.