Who should design my new system?

[Mepop]

I am considering having a boiler system with multiple air handlers with AC and computer controlled zoning installed for a new home. This type of system is a more expensive and it is for a 9500 SF house so I can't chance any design mistakes.

I want to put this work out to bid but I want everyone pricing exactly the same thing. Who do I turn to for the design of the system? Should I let an HVAC contractor design the system, do I need a mechanical engineer or who else? I don't want over kill and I don't want to waste money but it's got to be done right the first time!!!!! Any advice is greatly appreciated.

[roger g]

For the money you are going to spend I would want to speak some of their customers whoever you decide to pick.
You may get an engineer who designs well but the contractor installs lousey. Some contractors sub out to another contractor. A contractor might be good but maybe they have lost their best or only man and now they have new un tested workers. Of course they all SAY their work is guaranteed.
Just really do your home work and think what I have described.



roger

[Sparks]

What Roger said. There are also engineers that make mistakes in design, of course the engineers always blame the contractor. I would do a lot of homework on this one and talk to a lot of contractors as well as`design firms and ask alot of questions.

[Mepop]

Ok, I have been looking for good HVAC subs and they all say they can do this type of system but non of them seem to do much of it. So let start from another direction. What manufacturer sells the best boiler equipment out there? I will contact them to see what HVAC contractors purchase their equipment? Thanks

[roger g]

Purchasing doesn't mean much. A crappy boiler canw ork great if it is installed correctly and poorly installed good one is almost useless. You said have been looking at subs, did you ask them for customers with similar systems? A good design and a good install will make you happier than the reverse regardless of the equipment.


roger

[Sparks]

Well said Roger. MePop, I'm sure you're not hearing the responses that you would like to hear but they are the reality. Best bet is to get a lot of information and go with a design/ build contractor (engineer on staff) with a good reputation and references experienced in installations similar to yours.

[rabadger]

I would not let the contractor design the system. The contractor will never give you all the info you need two gather like for like pricing. You need to get a 3rd party involved. Where is the home going to be built?

Consider the following.

1. If you are going to build in the southern states cooling will be more critical. If you spend money on the boiler with multiple zones air handlers, hot water coils, and duct work you may never see the return on investment. Also in the southern states you may have a hard time finding a residential HVAC/Plumbing contractor that is knowledgable to service it.
Buy doing away with the boiler and replacing the air handlers with high eff. furnaces or heat pump air handlers you could save big bucks up front and zone each system into smaller zones. Your choices of qualified service contractors could be increased. You would be better off soaking the money into higher eff air conditioners.

2. If you are building in the northern states you may want to look at radiant floor heat. You could install multiple small boilers and smaller zones. The air conditioning could be seperate systems and if one system or zone goes down the entire home will not suffer.

Look at it this way. If the home requires 300,000 BTUH to heat it at design temperature you have to add all the natural losses that occure during the heat transfer process. Every time you transfer heat losses occure.

The boiler has three ratings. AGA Input MBH, AGA Gross Output MBH, and Net IBR rating MBH. I just opened a book. A top brand bioler has a Input of 427,000 BTUH, AGA Gross Output of 346,000, and Net IBR rating of 301,000.

But wait we aren't done yet. You now have to add for piping loss, domestic hot water heating (if required) and all the losses incurred during the transfer of hot air to the conditioned space. You could very well end up having to put in a money munching monster. When it comes to efficiencies boilers are not rated the same as warm air furnaces.

Bigger is not always better.

[Mepop]

Roger g, Sparks, rabadger, thanks much for your input and your thoughts are exactly what I want to hear. I have lived with a crappy HVAC heat pump system in my current home for thirteen years. It has cost me double the original installation costs in repairs and replacement parts also. I have lived with a crappy heat pump system in my current office building for the past nine years. It never fails; the system needs service at least twice a year because they are not working. As I type this message as I am sitting in a home with the windows open in 93% humidity and expecting 90+ degree weather for the fourth day in a row because the compressor went bad on the heat pump. Not to mention that my electric bills for both properties are double then similar properties. So you see when I talk about wanting the system that works the best, it because of past experiences. Ok, ok, enough with the complaining and moaning.

I live in Maryland and 90+ degree weather and high humidity is very common during the summer months so AC is critical to me. Can anyone recommend someone who is top notch to design the systems for our home? If you don’t know of someone, where should I start in order to find someone? Is it a mechanical engineer, should my architect be doing this? Thanks again for your comments!!!

[Sparks]

:) Or you could contact Rabadger and he could design it for you.

[rabadger]

I just looked up Maryland. Thats a bad place for a heat pump. Your winter design temp all over the state is to low.