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Read, "How HVAC myths get spread"

Do-it-yourself radiant...

The one exception we make is for simple do it yourself floor warming systems...

...that being a system which is not relied upon for space heating and where a qualified tradeperson is involved for gas and electrical work.

Prepackaged systems for the handy person are available from brand name pex pipe manufacturers through retail stores.

The better systems come with control appliances which are great looking factory built consumer goods and carry UL, CSA or cETLus certifications.

Multi zone control appliances for radiant heating
Factory built control appliances.

Final noted - HVAC is far more comprehensive than just keeping a person warm...a do it yourself floor warming system is just  that - a floor warming systems...
it is NOT an HVAC system.

So you plan on building to code...congratulations -  you get a "D".


Cost allocation Strategy

Net Zero Energy Buildings
You can spend 4% to 7% of construction cost on HVAC and get built to code construction - see cost allocation above, the minimum is shown on the left hand side) ....

...or you can invest 10% to 15% in the HVAC and building upgrades shown on the right above and obtain good  construction built to energy and indoor environmental standards.

You don't need a degree to figure out which one is best.

The origins of stuff in your home - how does HVAC play into this 'stuff'?

Ventilation pressurization and depressurization limits
Ventilation pressurization and depressurization limits - do you know what is safe?

HRV or ERV? How do you know which is best for your application?

How can this standard help you?

Correlation to HVAC and asthma? How do you know?

principles in HVAC
How do these principles play into HVAC?

codes and standards
Codes and standards - which one to follow - and how?




Do-It-Yourself HVAC - Should you do it?
Copyright (c) 2009 -2011, Robert Bean, All Rights Reserved
For additional support visit our visitor services page.

Our blanket statement is, "don’t do it"...and here's why:

HVAC is the most distorted term in construction and often completely misunderstood by consumers and even by seasoned industry professionals.

HVAC affects the health of the indoor environment and by association the health of the occupants; the consumption of utilities and thus monthly operating costs ergo ones cash flow; the temperature and humidity of building materials and furnishings thus the integrity of such things as musical instruments, paintings, furniture, cabinets and flooring etc.

HVAC is not just pipes, ducts furnaces and boilers. The following is the truest description of HVAC.

Heating influences relative humidity, surface and interstitial vapour pressures, building material durability, drafts and material emission rates.

Ergo the “H” in HVAC is not exclusively “heating comfort”.

Ventilation only facilitates the exchange of indoor air for outdoor air. It serves to condition the air, and it often (but not always) provides effective dilution of gases, odors, and particulate matter.

Ergo, the “V” in HVAC is not exclusively “air quality”.

Air-conditioning (AC) or  more appropriately,  “conditioning of
air”, facilitates decontamination, deodorization, dehumidification, humidification, temperature and air velocity control.

Ergo, the “AC” in HVAC is not exclusively “cooling comfort”.

So now you know why we suggest you work with design professionals and trades found through the certification processes offered through the industry associations – confirm that these individuals are also factory trained by leading manufactures and make sure these contractors are also recommended by the distribution chain.

Give them your list of expectations and let them worry about the details…

…or hang up your new shingle;

My Part Time Mechanical Services Inc.
 Specializing in self funded experiments related to health, building failures and energy use.


Background discussion:

Unless you spend 10% to 14% of the construction budget on the HVAC system or spend less on the mechanical and invest the savings into the building envelope in better insulation and windows (see image to the left) you will be paying for downgrades. That's right - downgrades. You can’t cheat reality.  In other words what you don’t spend on the building and mechanical system will ultimately show up in various combinations of building failures, discomfort, poor indoor air quality and high utility bills.

How can we say this?

Well study the graph below. It goes back to meeting minimum codes…3% to 5% gets you the bare minimum which is built to code construction (that's a "D" grade) and it’s one of the reasons why researchers find that roughly one in two consumers are not happy with their current indoor environments…but don’t feel bad - it’s worse for office workers,  students and residents of senior care facilities. 

...and just so you know - industry standards for thermal comfort and air quality are 80% to 85% satisfaction based on ASHRAE 55, 62.1 and 62.2.

Browse the internet for how many people are unhappy with their systems and not just a specific type  – all systems…too noisy… too drafty…too dry…to muggy….too smelly …too costly to run…never gets warm…can’t keep it cool…takes too long to heat up …heats up too fast - it doesn’t matter if it’s a heat pump, solar system, furnace or boiler – nothing  is immune from the consumer wrath…but if you dig deep the dissatisfaction is more often than not - a failure in design or installation or a failure in the building envelope…very rarely is it equipment failure.

Rule #1 with HVAC – its not what you get for 3% to’s what you didn’t pay for that will add discomfort and stress to your life.

Let’s say you can go to a hypothetical Wal-Mart type distributor of HVAC and buy all the components for a do-it-yourself system….then what? Now you’ve become the defacto mechanical contractor on the site and have to deal with the installation, commissioning and maintenance of the system. 

You want to become a mechanical contractor? I know seasoned mechanical contractors who don’t want to be mechanical contractors and you want to take on this task? Good luck.

Lets first talk the H in have to heat the occupants, the building, make up air and domestic water - plus any other toys like spa's pools and snow melt systems. So how much heat do you need? What does it mean if you have too much or not enough. Who is going to take responsibility for the design? This link will take you to what professionals do for designs...can you do your designer going to do this for you? Do you need a designer? This is a code requirement in many parts of North America - is it a requirement in your territory? If not - ask yourself why is it a code requirement in some place but not your place...remember these words from Lost in Space, "Danger, Will Robinson - danger".

So what’s your plan for the V in H-V-AC – the ventilation or the exchanging of indoor air for outdoor air? What will you do – take this on as well? You have many choices to make…a central exhaust system with or without make up air depending on which salesman you are dealing with. Maybe an HRV or an ERV…what’s the difference - maybe nothing at all – most salesmen don’t know  - how do you know? There are ventilation standards but they -  like the heating standards - are not always mandatory and in some jurisdiction not enforced even if the inspectors are aware of them.  Maybe where you’re building -  has high levels of outdoor air pollutants (garbage dump, meat packing plant, industrial fabricator or processing plants) in which case any ventilation system could make the indoor air quality worse. What about radon? Do you know what it is? Will you take on the radon management system if necessary? Do you know if you need one?

How about the AC in H-V-AC or air conditioning or more appropriately the conditioning of the air….humidification, dehumidification, filtration and temperature….will you take this on as well?  Do you need dehumidification and if so what method? Do you need humidification - and if so what should you use - a steam unit or water based evaporative type or worse a water mister? What type of filtration? How effective? Should you use a MERV 2 4, 8 or 12? What about filters with electrostatic charges? What will happen when someone tries to sell you a charcoal filter or UV lights...are they needed? Perhaps the worse case is someone trying to sell you an ozone generator or an electronic air cleaner which generates ozone…do you know what is right or wrong?  Anyone in the home have allergies? Anyone an asthmatic? Any seniors living in the home perhaps your mom or dad or both? Anyone with disabilities or physical ailments influenced by their environments. What about pets...any pets? Any musical instruments – guitars, piano’s etc? How about paintings or furniture – any old pieces that might be affected when you move into your new home with the home made HVAC system?

Presumably the Wal-Mart type distributor of HVAC stuff will be there for you the entire step of the way…though being the cheapest and the best makes most folks cock their heads like a puppy trying to understand what their master is saying….”cheap and best”….say it out loud “cheap and best”…has a nice ring to it if you believe it.

So lets just say you take on the role of mechanical contractor and do a complete DIY system.  

Then put yourself into the future - at a time when you have to sell your home which includes your home made HVAC system. Remember selling a home is a competitive sport … you want the buyers money and the buyer is going to look for reasons to pay you less.  They’ve been shopping around and know what is on the market…they’ve been into other people’s homes including their mechanical rooms – some HVAC systems look friendly some look like science experiments…some meet code – some don’t - if you were the buyer what would you be willing to pay for – given the choices available?

There are so many TV programs with titles like “sell this house” or “fix this house and sell it” and each episode the realtor and interior designers slam home the message to the seller – it’s not about what you like - it’s what the buyer likes. The potential buyer is not going to care about the homemade HVAC system…she (because it usually is a she who makes the decisions) - she is going to hire a mechanical contractor to look at the home made system and he (cause its usually a he) is going to tear the system apart – it’s what he gets paid to do. Everything he finds wrong is going to lower the price of your home.

Ok…all of the rhetoric heresy, sacrilege and disingenuous statements is a worst case scenario but you have a 50% chance of your home made HVAC system becoming a fiasco and you have a 50% chance of a contractor installed system becoming a fiasco….or you can have a 95% chance of getting a great system if you follow our advice on hiring a good contractor.

Once again…

Work with the professionals found through the certification processes offered through the industry associations – confirm that these individuals are also factory trained by leading manufacturers and make sure these contractors are also recommended by the distribution chain.

Give them your list of expectations and let them worry about the details…

Related reading:

Do I need an engineer? A Guide to HVAC/Indoor Climate Design Services
Where will your indoor climate system score?
How to "ball park" your budget for indoor climate control.
Indoor environments: Self assessment
Built to code: What does it mean for consumer thermal comfort?
The Total Comfort System - The "Un-minimum" System
Thermal Comfort: A 40 grit perspective for consumers
Thermal Comfort: A Condition of Mind

Do-It-Yourself HVAC - Should you do it?
The Cost of HVAC Systems - Are You Paying Too Much for Downgrades?
Radiant Installations - The Good, Bad and Ugly
Thermal Comfort Surveys - Post Occupancy, Part I
Thermal Comfort Surveys - Post Occupancy, Part II

For additional support on this topic visit our visitor services page.

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