weil Mclain ultra oil, 2 hydro coils, outdoor reset?

Unknown

Hi All,

New to the site, was referred by a buddy who's also in the business.



I am about to install a new weil mclain ultra oil with a reillo burner in place of an existing burnham oil boiler.  The house has 2 hydro units, one in the basement one in the attic.  It also has a existing 40gallon indirect tank. 

We are located in new england just south of boston. 

My main question/concern is:  Would the outdoor reset option be viable for this setup/location with the hydro units?  My concern is that I do not want the hydro units to blow cool air if on a warm day the outdoor reset is only sending 130F water etc.  If I bump up the outdoor reset...it is, or seems, almost like not having one in the first place (or less of an advantage anyway).  So, what is the consensus on an outdoor reset with 2 hydro air handlers, 1 40G indirect with a WM ultra oil UO-3/Reillo.

For the reset, my supplier is wanting to sell me the taco pc-700 with a 3 zone priority board, expandable, so that the 700 simply plugs in.



Also, just want to confirm that these boilers can be piped conventionally...(i.e. without a primary/secondary loop) as we want to re-use the old piping which is only 5 years old.



Thanks in advance,

-John

Paul Fredricks_3

depends

I think we talked about this recently. If the hydro coils are sized to the load then you may have an issue with cold air. I know the coils in the First Company units always seem to be oversized, so you can get away with a somewhat lower water temp. You can also slow the fan speed to help keep the TD up.



I can't tell you from personal experience if this will save money or not, but anytime you lower the water temp below where it would normally be you lessen the stand by loss, and that saves.

Unknown

info on air handlers

The air handlers are ADP's.  I do not know much about this company at all.  I do know that the unit in the attic only has one fan speed which is not adjustable.  I was going to re-wire the fan motor for high speed as the AC is barely working due to the trickle of air on the 2nd floor.  The basement (1st floor) unit I have not looked at all.  Its fan seems to be quite a bit faster than the 2nd floors though so I am not sure if its the same unit...something I'd have to look at.  I also did not look at sizing yet...so I am not sure, but I would guess the sizing is pretty close (ie tight).  The builder blasted these houses up about 6 years ago and I am not certain everything was done 100%.

Based on this, I am now really concerned about using an outdoor reset.  We do not want to get into re-configuring the air handler and going back and tweaking temps etc. countless times to get things right.  I'd like to install it, and have it work correctly from go. 

Another option is using the outdoor reset and setting up the parameters so that it is cutting down some temps, but not as much as normal, but then we are getting to the route of the question...is it worth it....and how much tweaking (i.e. call backs) will it take to get it 100% acceptable.   ;-0

Thanks any thoughts, much aprreciated!



-John

Paul Fredricks_3

Don't know

I don't think anyone can answer the "Is it worth it" question with any certainty. Just too many variables.



Not a fan of ADP, kind of cheap. What you could do is swap out the existing blower motor with a multi speed, set the heat to low speed, lower the boiler temp, and see what you get for temp rise. Of course, the customer has to be interested in the experiment. If they are interested in saving money and are interested in going for the ODR, do the experiment at cost. This way you gain some knowledge and, if it doesn't work out, they don't feel they wasted a ton of money.



Just an idea.

CMadatMe

Slow down the flow rate

For starters hydro-air brings on an oversized heating load. What I mean is that the btu out-put on the heat side is 99.9 percent of the time oversized for the heat loss of the structure because it is sized for the cooling load and not the heat load. For example, a 3 ton air handler will give you basically 60,000 btu output. What size Air Handler do you have? How about attacking it by doing the reset but slowing down your flowrate through the coil and give yourself a larger delta-t.