(Reuters) -British engineering firm Smiths Group on Tuesday missed annual profit expectations, hurt by subdued demand for its heating, ventilation and air conditioning products, and sending its shares as much as 8% lower.

The company also said it was buying U.S.-based Modular Metal Fabricators and Canada's Wattco for a combined 110 million pounds ($147 million) to further expand in the Americas, its biggest market by revenue.

The more than 170-year-old company has been grappling with a sluggish construction and semiconductor market in the United States, weighing on revenues at its Flex-Tek and Smiths Interconnect divisions.

The acquired companies will be integrated into the Flex-Tek division, which provides engineered components that heat and move liquids and gases for the construction, industrial and aerospace markets, Smiths said.

They tie in with the business acceleration programme launched by CEO Roland Carter, a company insider who took the helm in March, targeting 30-35 million pounds of savings in fiscal year 2027.

"The acceleration plan will have minimal headline impact in FY25, as we take associated costs below the line, and benefits will begin to phase in during FY26," finance chief Clare Scherrer said on a call with analysts.

Smiths shares fell to the bottom of the FTSE 100 index, but have risen about 8% since Carter took over as CEO.

"We will increase the importance of moving into new, higher-growth adjacencies with targeted allocation of our R&D resources," said the company, whose baggage-screening kit and explosive detectors are a common sight at airports.

Mergers and acquisitions offer additional opportunities, it added.

Smiths reported headline operating profit of 526 million pounds for the year ended July 31, below analysts' consensus forecast of 535 million pounds, according to a company poll.

The London-based company said it expected organic revenue growth of 4%-6% for fiscal 2025, versus estimates of 5.8%.

($1 = 0.7488 pounds)

(Reporting by Shanima A and Yamini Kalia in Bengaluru; Editing by Rashmi Aich and Mark Potter)