Practical HVAC and plumbing guidance from a licensed New Hampshire contractor serving the Lakes Region south.https://www.cdmechanical.net/en-ushttps://www.cdmechanical.net/blog/what-counts-as-an-emergency/https://www.cdmechanical.net/blog/what-counts-as-an-emergency/What genuinely needs somebody out tonight, what can wait until morning, and what you should handle yourself before calling anyone.Tue, 14 Jul 2026 00:00:00 GMTtroubleshootingmaintenanceDerek Millshttps://www.cdmechanical.net/blog/ductwork-problems-older-homes/https://www.cdmechanical.net/blog/ductwork-problems-older-homes/If one room has never been comfortable, the equipment is probably not the problem. What goes wrong in older duct systems and what is worth fixing.Tue, 10 Mar 2026 00:00:00 GMTfurnacesnew-hampshireindoor-airChris Wheelerhttps://www.cdmechanical.net/blog/oil-to-heat-pump-conversion/https://www.cdmechanical.net/blog/oil-to-heat-pump-conversion/Leaving oil behind is one of the most common projects we do. The realistic sequence, the decisions along the way, and what to do about the old tank.Tue, 13 Jan 2026 00:00:00 GMTfurnacesheat-pumpsbuying-guideenergy-costsChris Wheelerhttps://www.cdmechanical.net/blog/winter-humidity-and-humidifiers/https://www.cdmechanical.net/blog/winter-humidity-and-humidifiers/Static shocks, cracked woodwork, and dry sinuses every January. Where the moisture goes and why a bigger humidifier is not always the answer.Tue, 09 Dec 2025 00:00:00 GMTindoor-airwinter-prepChris Wheelerhttps://www.cdmechanical.net/blog/how-long-does-a-furnace-last/https://www.cdmechanical.net/blog/how-long-does-a-furnace-last/Age alone is a poor reason to replace working equipment. The five questions that actually decide repair versus replace.Tue, 14 Oct 2025 00:00:00 GMTfurnacesbuying-guideChris Wheelerhttps://www.cdmechanical.net/blog/radiant-floor-heat-guide/https://www.cdmechanical.net/blog/radiant-floor-heat-guide/The most comfortable heat there is, with real constraints on where it makes sense. Retrofit versus new construction, floor coverings, and response time.Tue, 16 Sep 2025 00:00:00 GMTboilersbuying-guideChris Wheelerhttps://www.cdmechanical.net/blog/iron-and-sediment-filtration/https://www.cdmechanical.net/blog/iron-and-sediment-filtration/Orange staining, black specks, and sand in the aerators are three different problems with three different fixes. A softener is not always the answer.Tue, 12 Aug 2025 00:00:00 GMTwater-treatmenttroubleshootingDerek Millshttps://www.cdmechanical.net/blog/commercial-maintenance-plans/https://www.cdmechanical.net/blog/commercial-maintenance-plans/Most agreements are priced per visit and say very little about what happens on the visit. What to require before you sign one.Tue, 15 Jul 2025 00:00:00 GMTcommercial-hvacmaintenanceChris Wheelerhttps://www.cdmechanical.net/blog/mini-split-musty-smell/https://www.cdmechanical.net/blog/mini-split-musty-smell/That damp gym-bag smell has one common cause and one uncommon one. Neither of them is fixed by an air freshener.Tue, 10 Jun 2025 00:00:00 GMTmini-splitstroubleshootingindoor-airDerek Millshttps://www.cdmechanical.net/blog/spring-ac-tune-up/https://www.cdmechanical.net/blog/spring-ac-tune-up/What a real tune up includes, what you can do yourself in twenty minutes, and how to tell a genuine service from a sticker on the side of the unit.Tue, 13 May 2025 00:00:00 GMTair-conditioningmaintenanceDerek Millshttps://www.cdmechanical.net/blog/water-heater-types-compared/https://www.cdmechanical.net/blog/water-heater-types-compared/Three good options with genuinely different tradeoffs. Which one fits depends on your house, your water, and how your household actually uses hot water.Tue, 11 Mar 2025 00:00:00 GMTplumbingbuying-guideenergy-costsChris Wheelerhttps://www.cdmechanical.net/blog/heat-pump-auxiliary-heat/https://www.cdmechanical.net/blog/heat-pump-auxiliary-heat/Aux heat is normal in a cold snap and expensive if it runs all the time. How to tell which one you have.Tue, 21 Jan 2025 00:00:00 GMTheat-pumpsenergy-coststroubleshootingDerek Millshttps://www.cdmechanical.net/blog/heat-out-what-to-do/https://www.cdmechanical.net/blog/heat-out-what-to-do/Six checks that solve a real share of no-heat calls, what to do about the house while you wait, and when to stop and call immediately.Tue, 17 Dec 2024 00:00:00 GMTwinter-preptroubleshootingnew-hampshireDerek Millshttps://www.cdmechanical.net/blog/condensing-boiler-worth-it/https://www.cdmechanical.net/blog/condensing-boiler-worth-it/High efficiency boilers earn their rating only under conditions a lot of existing houses do not give them. How to tell if yours will.Tue, 05 Nov 2024 00:00:00 GMTboilersbuying-guideenergy-costsChris Wheelerhttps://www.cdmechanical.net/blog/heat-pump-efficiency-ratings/https://www.cdmechanical.net/blog/heat-pump-efficiency-ratings/Efficiency ratings are real but they are lab numbers. What they mean, and the specification that matters more than any of them in a cold climate.Tue, 10 Sep 2024 00:00:00 GMTheat-pumpsenergy-costsbuying-guideChris Wheelerhttps://www.cdmechanical.net/blog/summer-humidity-old-houses/https://www.cdmechanical.net/blog/summer-humidity-old-houses/Seventy two degrees and still sticky usually means a humidity problem, not a cooling problem. Often the air conditioner is the cause.Tue, 06 Aug 2024 00:00:00 GMTair-conditioningindoor-airnew-hampshireChris Wheelerhttps://www.cdmechanical.net/blog/frozen-ac-coil/https://www.cdmechanical.net/blog/frozen-ac-coil/Ice on an air conditioner in July looks backwards and always means one of two things. How to thaw it safely and stop it recurring.Tue, 09 Jul 2024 00:00:00 GMTair-conditioningtroubleshootingDerek Millshttps://www.cdmechanical.net/blog/hard-water-softeners/https://www.cdmechanical.net/blog/hard-water-softeners/Hardness is not a health problem, it is an equipment problem. What scale does to a water heater and how to size a softener properly.Tue, 11 Jun 2024 00:00:00 GMTwater-treatmentnew-hampshireChris Wheelerhttps://www.cdmechanical.net/blog/rooftop-unit-maintenance/https://www.cdmechanical.net/blog/rooftop-unit-maintenance/RTUs are out of sight and they stay that way until the tenants complain. What a real quarterly service covers and the failures that come from skipping it.Tue, 14 May 2024 00:00:00 GMTcommercial-hvacmaintenanceDerek Millshttps://www.cdmechanical.net/blog/mini-split-maintenance/https://www.cdmechanical.net/blog/mini-split-maintenance/Ductless systems are low maintenance, not no maintenance. The filters you should be rinsing monthly and the deep clean that needs a tech.Tue, 16 Apr 2024 00:00:00 GMTmini-splitsmaintenanceDerek Millshttps://www.cdmechanical.net/blog/single-vs-multi-zone-mini-split/https://www.cdmechanical.net/blog/single-vs-multi-zone-mini-split/Multi zone systems look like the obvious choice on paper. Here is where they work well and where separate single zone units are the better buy.Tue, 12 Mar 2024 00:00:00 GMTmini-splitsbuying-guideChris Wheelerhttps://www.cdmechanical.net/blog/heat-pump-blowing-cold-air/https://www.cdmechanical.net/blog/heat-pump-blowing-cold-air/A heat pump that feels like it is blowing cool air is usually working fine. Here is how to tell the normal reasons from the ones worth a service call.Sun, 14 Jan 2024 00:00:00 GMTheat-pumpstroubleshootingDerek Millshttps://www.cdmechanical.net/blog/furnace-short-cycling/https://www.cdmechanical.net/blog/furnace-short-cycling/Short cycling wears equipment out early and it is almost always one of five things. Two of them you can check without tools.Tue, 12 Dec 2023 00:00:00 GMTfurnacestroubleshootingDerek Millshttps://www.cdmechanical.net/blog/boiler-pressure-gauge/https://www.cdmechanical.net/blog/boiler-pressure-gauge/Where the needle belongs on a residential boiler, what sends it too high or too low, and which of those you can safely deal with yourself.Tue, 14 Nov 2023 00:00:00 GMTboilerstroubleshootingDerek Millshttps://www.cdmechanical.net/blog/heat-pump-vs-furnace-new-hampshire/https://www.cdmechanical.net/blog/heat-pump-vs-furnace-new-hampshire/Cold climate heat pumps really do work here, but they are not the right answer for every house. What we look at before recommending one.Tue, 17 Oct 2023 00:00:00 GMTheat-pumpsfurnacesbuying-guidenew-hampshireenergy-costsChris Wheelerhttps://www.cdmechanical.net/blog/bleeding-radiators-air-in-system/https://www.cdmechanical.net/blog/bleeding-radiators-air-in-system/Air in the loop is one of the most common heating complaints and one of the few you can genuinely fix yourself. The order matters.Tue, 03 Oct 2023 00:00:00 GMTboilersmaintenancetroubleshootingDerek Millshttps://www.cdmechanical.net/blog/winter-prep-checklist/https://www.cdmechanical.net/blog/winter-prep-checklist/A fall checklist worth working through in October, when a problem is an appointment instead of an emergency.Tue, 26 Sep 2023 00:00:00 GMTwinter-prepmaintenancenew-hampshireChris Wheelerhttps://www.cdmechanical.net/blog/water-heater-noises/https://www.cdmechanical.net/blog/water-heater-noises/Popping, rumbling, and a high whine are three different problems. One is nearly always sediment and one means shut it off now.Tue, 12 Sep 2023 00:00:00 GMTplumbingtroubleshootingDerek Millshttps://www.cdmechanical.net/blog/repair-or-replace-decision/https://www.cdmechanical.net/blog/repair-or-replace-decision/A framework for deciding, including the parts of the calculation that have nothing to do with the price of the repair.Tue, 08 Aug 2023 00:00:00 GMTbuying-guidemaintenanceChris Wheelerhttps://www.cdmechanical.net/blog/ac-not-cooling/https://www.cdmechanical.net/blog/ac-not-cooling/Four things a homeowner can check in ten minutes, and the symptoms that mean you should stop and pick up the phone instead.Tue, 11 Jul 2023 00:00:00 GMTair-conditioningtroubleshootingDerek Millshttps://www.cdmechanical.net/blog/well-water-testing/https://www.cdmechanical.net/blog/well-water-testing/About half the state is on private wells with no required testing. What actually shows up in our groundwater and which results call for treatment.Tue, 13 Jun 2023 00:00:00 GMTwater-treatmentnew-hampshireChris Wheelerhttps://www.cdmechanical.net/blog/mini-split-sizing/https://www.cdmechanical.net/blog/mini-split-sizing/Square footage charts get this wrong more often than they get it right. What actually determines the size of a ductless system, and why oversizing hurts.Tue, 09 May 2023 00:00:00 GMTmini-splitsbuying-guideChris Wheelerhttps://www.cdmechanical.net/blog/baseboard-not-getting-hot/https://www.cdmechanical.net/blog/baseboard-not-getting-hot/One cold zone, one cold room, or the whole house cold are three different problems. Sorting out which one you have narrows it down fast.Tue, 06 Dec 2022 00:00:00 GMTboilerstroubleshootingDerek Millshttps://www.cdmechanical.net/blog/preventing-frozen-pipes/https://www.cdmechanical.net/blog/preventing-frozen-pipes/Which pipes actually freeze, what to do before the cold snap, and what to do in the first ten minutes if one already has.Tue, 15 Nov 2022 00:00:00 GMTplumbingwinter-prepnew-hampshireDerek Millshttps://www.cdmechanical.net/blog/furnace-filter-how-often/https://www.cdmechanical.net/blog/furnace-filter-how-often/The number on the box assumes a house that does not exist. What actually determines your interval, and why a thicker filter is not always better.Tue, 11 Oct 2022 00:00:00 GMTfurnacesmaintenanceindoor-airDerek Millshttps://www.cdmechanical.net/blog/questions-to-ask-hvac-contractor/https://www.cdmechanical.net/blog/questions-to-ask-hvac-contractor/License, insurance, and eight questions that separate a contractor who measured your house from one who read a number off a chart.Tue, 20 Sep 2022 00:00:00 GMTbuying-guidenew-hampshireChris Wheeler