Boilers, furnaces and stoves: Correlation
Prices it moves with, and why
The index covers heating equipment such as boilers and stoves. Prices follow steel, castings, burners and controls plus labour; demand follows building and industrial activity, and the relative price of gas, oil and electricity decides which heating wins.
Price index US PPI: heating equipment except warm air furnaces index · monthly, Jan 2006 to Sep 2026What its price moves with
Selected linkBoilers, furnaces and stoves and Steel
Monthly changes 0.09 little or none correlation 12-month changes 0.23 weak correlation Last 5 years -0.07 monthly changes Lead or lag +6 mo Steel tends to lead by 6 months (r 0.35) Price function, Jan 2006 to Sep 2026 Boilers, furnaces and stoves ≈ 7.40 × (Steel)0.69 R² 0.62 On this fit, a 10% higher steel price goes with a 6.8% higher boilers, furnaces and stoves price over the long run. Units: index and index, BLS base period.Chart: Boilers, furnaces and stoves and Steel prices rebased to 100 at Jan 2006, log scale
Both prices rebased to 100 at Jan 2006, on a log scale so equal percentage moves look the same size.Chart: Boilers, furnaces and stoves price against Steel price, monthly, log scales, with fitted line
Each dot is one month; paler dots are older (2006), darker dots recent (2026); the ringed dot is the latest month. The dashed line is the fitted price function. Both axes are logarithmic.Boiler shells, heat exchangers and furnace casings are steel or cast iron. Yet yearly moves correlate at only 0.23 with the steel index, since equipment is sold on price lists that change once or twice a year and labour and parts matter too.
little or none co-movement month to month · 249 months Show chartsMost boilers and furnaces burn natural gas, so gas supply and price shape demand for new equipment. The link is weak in the data, because the US equipment index reflects manufacturing costs more than fuel markets.
little or none co-movement month to month · 249 months Show chartsHeat pumps are taking share from gas boilers as policies push electrification. The two indices correlate at 0.40 monthly and 0.91 yearly, but this is a common driver: both are made by similar firms facing the same US cost inflation.
moderate co-movement month to month · 249 months Show chartsLPG fuels stoves and heaters where piped gas is absent, including most Indian kitchens. Propane prices swing with oil and gas, but the equipment index does not follow, with monthly moves correlating at -0.03, as stove prices depend on manufacturing costs.
little or none co-movement month to month · 248 months Show chartsWood and pellet boilers and biomass cookstoves burn wood chips, pellets and residues. The wood chip proxy correlates at 0.54 yearly with the heating index, partly shared demand for heating and partly general US price trends.
little or none co-movement month to month · 178 months Show chartsLarge biomass and industrial boilers come from the same fabricators as smaller heating equipment. The boiler proxy correlates at 0.68 yearly and 0.21 monthly with this index, reflecting shared steel fabrication costs and industrial demand.
weak co-movement month to month · 249 months Show chartsHow to read these numbers
Correlation of monthly changes (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak.
12-month changes compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs.
Price function is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation.
Lead or lag checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months.
Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link.
Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site.