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Advice on New Hydro Air System

Fsmith432 Member Posts: 1
<span style="font-size:12pt">Hello - Been reading old threads for a while so figured I'd post my question directly.  My house is a ranch style home that was built in 1964. It has a walk out finished basement.  Current heating for that portion of the house is done via Williamson oil furnace/hot air system (approx. 25 years old).  DHW is from a direct fired John Wood oil water heater.  In 1990 the prior owners added an addition to the side of the house that has two large bedrooms with lots of windows over an unheated garage.  That end of the house is heated by electric baseboard heaters.  Currently no A/C in the house at all, which we would like to add.  Total conditioned sq footage is approx. ~3,100 sq ft. We are located in MA, south of Boston.  Electricity is approx. $0.194/kwh.  We've had 3 companies give us quotes, and our plan is to go with the following hydro air system which would add A/C and replace the electric baseboard heat.  Gas is not an option where we live.</span>

<span style="font-size:12pt">-Weil McLain Ultra Oil 3 boiler</span>

<span style="font-size:12pt">-2 zones of hydro air (one AH in the attic over the addition and one in the mechanical room in the finished basement to tie into the existing duct work for the rest of the house). They will be installing new ductwork in the attic to heat/cool the addition zone over the garage.</span>

<span style="font-size:12pt">-2 H2O, AXQ056-C heat coils, one for each zone.</span>

<span style="font-size:12pt">-3 ton Heil FVM4X3600A 16 SEER air handler in basement</span>

<span style="font-size:12pt">-2 ton Heil FVM4X2400A 16 SEER air hander in attic above addition</span>

<span style="font-size:12pt">-3 ton Heil HXA636GKA 16 SEER condenser for main portion of house</span>

<span style="font-size:12pt">-2 ton Heil HXA624GKA 16 SEER condenser for addition</span>

<span style="font-size:12pt">-SuperStor 60gal indirect water tank w/ priority</span>

<span style="font-size:12pt"> </span>

<span style="font-size:12pt">Questions:</span>

<span style="font-size:12pt">1.  Any experience with the WM Ultra Oil systems?  Seems that WM has a good following in the area and my installer has experience with this brand. Most quoted the WGO-3 or WGO-4 gold, but after some research I wanted a 3 pass system so moved to the UO-3.</span>

<span style="font-size:12pt">2.  My contractor did a manual J at my request as it is necessary for some local financing incentives that are available.  I think he did it more for the cooling aspect (which is what it is required for) vs. the heating.  His numbers came up with approx. 42k btuh for cooling and 99k btuh for heating.  However he omitted certain things such as fireplaces, etc which do not appear to factor in to the cooling calc but materially impact the heating calc. I downloaded HVAC calc and did my own room by room calculations.  I came up with similar numbers for cooling (~40k-45k btuh for cooling) but my heating numbers came out at approx. ~127k.  So it appears that the cooling will be slightly oversized at 5 tons of total capacity vs a 4 ton need based on the manual J. Thoughts on this? On the heating side, am I cutting it too close with the UO-3 that is rated for 122k btuh output?</span>

<span style="font-size:12pt">3. The heat coil's spec sheet indicates that they are rated for 56k btuh @ 800cfm.  Based on my room by room HVAC calc numbers, the addition area needs less (~40k btuh) and the main part of the house and basement which are on the other zone need more (~87k btuh).  Based on the capacity of the heat coils, are we going to be cold in the main part of the house?  It looks like the heat coils can produce more heat at higher CFM, but i'm not sure about the CFM range of the air handlers as I think they are designed more for cooling and the contractor is somehow tying in the heat coils.  He originally quoted a first air system but we couldn't get an AHRI certificate for 16 SEER with that air handler so he switched to the configuration quoted above.  Am I thinking about this right?</span>

<span style="font-size:12pt">4. The other quotes we got both had a 45 gal superstor, vs this quote at 60 gal.  Any view on which is more appropriate?  We have two showers with 1.5gpm heads, then dishwasher, clothes washer, kitchen sink, etc, obviously not all calling for hot water at the same time.  I think our current direct fired tank is ~30-40 gal.  we sometimes run out of hot water if both showers are going at once but its not a huge problem.

</span>5.  Any other suggestions/considerations?  Thanks in advance.


  • heatpro02920
    heatpro02920 Member Posts: 991
    Keep getting quotes..

    All contractors are going to do it different.. I am kind of confused...

    If they are putting hydro-air units in, why the need for separate AC units and hot coils?

    Here is what I am thinking, off the top of my head with out seeing the property..

    If cost is not a huge issue here is what I would do....

    2 first co units... EVB-HW's heatpump/ac and HW coil....



    I would add an additional hw coil to the duct work over each hydro air unit to allow you to lower your boiler temps...

    2- Armstrong air 16 seer heatpump outdoor units


    and 1-4SHP16LS136P-2

    For DHW I would look into the Smart tanks, do the math to see what size you need and properly size the unit, no exceptions on that one, bigger inst better unless you need it, otherwise it is a waste..

    I would use a Grundfos alpha on the primary side and a Bumble bee pump setup for delta T on the secondary side for each air handler and the dhw tank....

    1-Buderus 2 G115-3's fire them with .55 nozzles {or figure out what your heat loss really is and fire them accordingly} with a multi boiler control like the weil mclain BCP3 , use a nice tstat that controls heatpump cross over, have the rite tech set it all up and you will have one of the most efficient Oil/electric systems available, as well as a bunch of rebates if they are still good by the time you do the work... I would configure them direct vent vs chimney and use outside air, even if you use a chimney you can still use outside air...

    Pipe the twins primary secondary start with as low of a boiler temp as you can, the controls will allow you to play with all the settings once you get going...

    So depending on the cost of your power and your units, you would run your heat pumps to say.. 40 degrees, once 40 degrees outside temp is hit, you will switch to a single buderus boiler, once more than that boilers output is needed to heat the space you will bring in #2, your boiler temp could be as low as 140 and your boiler will still be able to be setup to run up to 180 for your DHW tank, which shouldn't call much...

    Now if cost is an issue, then I would use a single properly sized buderus boiler {I like using twins when homes have heat losses over 130K you are on the edge..}, omit the heatpumps and use 13 seer units, change the variable speed first co's to regular HBXB-HW's, Lose the boiler control and run the control that comes with the g115 and again the same properly sized water tank, then 007's for circulation...

    With the price of oil depending how long you will be at this address I would be investing as much into efficiency as you can afford, heatpuump, multi stage boilers will save you money, how much will depend on your heat loss and what the price of oil does, but sometimes the above system vs your proposals isnt a huge amount....