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Question DetailsAsked on 2/21/2015

How often should my gas boiler be inspected/cleaned?

This week, our gas boiler heating system stopped working. The repair man said it may have had something to do with the fact that the gas boiler was dirty. How often should I have the gas boiler inspected/cleaned to prevent this from happening again?

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You don't say WHAT failed - but certainly if the boiler itself cracked due to overheating or the circulating pump gave up the ghost, failing to flush out the furnace each year could have caused that after years of neglect. Or if flame rolled out of the firebox, could be the burners were buried in dirt and rust. Or if boiler cracked due to going dry, failure to check the inlet regulating valve and pressure tank.

Should be looked at every year is the recommendation - at least every 2 years even if you are going to be a skinflint and unit is in clean operating environment, in my opinion. Typically about $50-75 cost on a pre-season special, or about $75-150 during peak (fall) season or during winter heating system repair season.

Typical things an annual cleaning/servicing does include (off the cuff, not a definitive list nor in any specific order, and mixes furnace/boiler items to some extent):

1) general visual once-over for signs of leaks, kinked pipes, corrosion, damage, burnt insulation on wires, disconnected or buckled ducting, collapsing support platform, sooting up, etc

2) check for damaged/obviously leaking or corroded pipes or ducts

3) cleaning burners to remove dust and dirt (and possibly rust), which makes for a safer flame as well as more efficient burning, so saves money too by wasting less combustion heat

4) replacing thermocouple or testing ignitor, and checking pilot is burning right

5) listening to operation, especially for noise in the circulating pump or fan

6) with higher efficiency units, confirming damper and exhaust fan are kicking on correctly and working right

7) check for required safety devices and test for correct operation - overtemp/overpressure valve, secondary high-temp safety cutoff switch, pressure/temperature gauge, additional various safety sensors and automatic shutoffs on newer units depending on age and make/model

8) check for correct operation of zone valves or zone dampers, and that each zone is actually getting good heat when thermostat calls for it (and that thermostat is properly calling for heat and then shutting it off as programmed)

9) check (or remind owner) that batteries in electronic thermostats need annual replacement

10) clean firebox as needed

11) inspect firebox, boiler, heat exchanger for excessive rust, aluminum corrosion, cracking, blockage of exhausst gas flueways

12) drain sediment from bottom of boiler

13) occasionally, depending on how clean incoming air is or if there is local source of dirt (dirty garage floor from car droppings or workshop dust), additional cost for about 1 hour work tuypically for manual brush/compressed air cleaning of the airways through the boiler or heat exchanger. Typically about every 10 years or so is probably a typical needed frequency or this in normal conditions. Extends life of unit because built up burned-on dust causes hot spots that can cause cracking, plus built up dust (which is usually a partly-burned carbon layer so a good insulator) also significantly reduces the heat transfer from the hot gases and the conditioned air or water, as applicable. I know in mine, first time I did it (in a garage used as repair and woodworking workshop too) it cut the heating time to come back up to operating temp by more than a third - so 10 years dust was costing me about 30% in additional gas for heating. Dropped my overall (boiler and hot water) heating bill year over year over $300.

Normal servicing (without any substantial repairs or full boiler/evaporator airway cleaning) typically takes about 30-45 minutes on simple older non-electronic units, 1-1.5 hours on more complex newer units and ones with multiple individually controlled (forced air furnace) zones, or smart home system.

Of course, leaks or defective sensors or such take more time and cost, but as long as unit is running and working OK and without unusual noises, generally not more than an additional $50-200 depending on issue, if any. Major exception with forced air furnaces - if heat exchanger is cracked, then looking at typically around $300 bare minimum and up to closer to $1000 in some newer units. Have your original paperwork out before calling if you have a forced air furnace so you know IN ADVANCE if your heat exchanger is still in warranty - typically does NOT cover the replacement cost (which is 1/3-1/2 the total replacement cost typically), but still better than no coverage. Note - generally have to go through manufacturer for replacement for warranty coverage. Some are REAL nasty - only cover the replacement if the old heat exchanger is shipped to them FIRST for inspection, then they ship new heat exchanger to you for installation - so you are out a couple hundred $ on expedited shipping, then maybe as much as a week or two to get the new one - good way to be sure they never have to pay for the replacement, since most failures would be detected when the furnace is needed immediately. Even saw one where defective units had to be shipped to Japan for inspection and the company guaranteed replacement (if found to be defective, in their opinion) witin 2 weeks of receipt, shipping of new one from Japan by sea - so a month or more replacement time ! One reason to read warranties CLOSELY, and you get better service if the installing company is an authorized repair rep of the company.

Answered 4 years ago by LCD

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