Manual J contractor

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Mev

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I'm in Northeast Massachusetts. We have gotten some estimates on a mini-split system with 2 heads. This is not for the whole house, it is just what we can afford to do at this time, and to tackle the 2 worst areas in the house during the summer. Heating during the winter would be a positive, but we have a 5 year old high efficiency gas condensing boiler and baseboards all thru the house.
The first head would go in the 16x11 sunroom with 3 exterior walls (S,W,and East) and a 7'x7' opening into a large kitchen. The head would be positioned on the south wall directly facing the opening into the kitchen. The hope is that it could cool and heat the sunroom and kitchen. There is no baseboard in the kitchen.
The second head would be on the third floor which is 36'x28' with windows on the east side and 2 large skylights on the south side. I was hoping that this head could cool this floor and also take care of the heat that naturally rises from the lower floors through doorways and stairways that are always opened.
I have gotten quotes that range from 24K outdoor unit with 2 12K heads for around $11k, to a 24K outdoor unit and 15K for the sunroom and 18K for the third floor for $18K.
Everyone else is in-between. No one did a Manual J, just simple questions about insulation and about half took dimensions.

I've tried simple load calcs myself and tried simple and a little more complicated CoolCalc runs, but I don't trust what I've done (ex. don't see where to specify skylights for specific rooms or sliding doors for specific rooms, knee walls, slanted walls,....):
Sunroom and Kitchen: 13K cooling, 15K heating
3rd floor: 6K cooling, 7K heating

Can anyone recommend someone in my area to do a real manual J?

Thanks,
Mark
 

Mev

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I have no idea if this helps in any way. I looked at my natural gas usage for heating the house and it averages 1000 therms per year at worse. Very roughly estimating my boiler efficiency at 90% at best. So I needed 90,000K BTUs/year at worse to heat my house.
I followed instructions from green building advisor to calculate btus/hr needed and I got ~61KBTU/hr which is close to my last coolcalc of 69KBTUs/hr.
 
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John Gayewski

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Most contractors won't do the manual J until you have a contract with them and they are going to do the job. They usually estimate first then when it comes time to install the equipment they should do it. Did you ask for this to be done?
 

Mev

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Most contractors won't do the manual J until you have a contract with them and they are going to do the job. They usually estimate first then when it comes time to install the equipment they should do it. Did you ask for this to be done?
I did not ask for that, and not a single one said anything about doing a manual J.
 

Fitter30

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There is no way a mini manufacturer would sign off using a 24k condenser for 33k indoor units. You might want to consider hyper heat equipment. All heat pumps lose btu the colder it gets. Standard heat is tested at 47° and 17° calling the factory can get other temps for btu rating but need condenser a inside unit models.
 

Mev

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There is no way a mini manufacturer would sign off using a 24k condenser for 33k indoor units. You might want to consider hyper heat equipment. All heat pumps lose btu the colder it gets. Standard heat is tested at 47° and 17° calling the factory can get other temps for btu rating but need condenser a inside unit models.
The guy who quoted me the 24K outdoor unit and the 15K and 18K indoor units pointed me to Daiken's installation pdf:
Multi-Zone Combination Table
Install the indoor unit according to the table below, which shows the relationship between the class of indoor unit and the corresponding port.
The total indoor unit capacity that can be connected to this unit:
3MXL24* – Up to 39,000 Btu/h
 
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