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[terpjr]

Good Morning and Happy Turkey Day
I have a Woodmaster 4400, have had it for 7 years now...very happy with my set up
I use it to heat an old farmhouse that has undergone a complete renovation.
The house totals out to about 3000 square feet, some larger spaces and vaulted ceilings.
WWe use hot-water baseboard and heat our hot water with it as well.
When we first purchased the furnace we were only heating half of the house.
The renovation has been done in stages and for 6 years we have had 1/2 of the house finished.
Now that the other half has been opened up, insulated and finished, we have installed heat.
There are now three zones operating.
Should I assess my heat exchanger size/capacity?  I am producing enough heat for the house bbut, as we are just getting into the true heating season, I am wondering about my efficiency - would a larger heat exchanger be more efficient? 
Just looking for a little info.
Thanks!

[fireboss]

What size do you have now.? I have a 40 plate and heating 3000 sq  and have no problems my house is only 20Yrs old and new windows

[terpjr]

How do I figure out size.  I have long forgot

[idahohay]

terpjr, i'm curious as to what the pro's advise as I am about to purchase a BPHE.  I sounds like you have separated the wood boiler loop from your interior zones with a flat plate heat exchanger.  Your boiler side being non pressurized, and your interior zones being pressurized?  Just clarifying that you were not referring to the baseboards whose size/capacity was in question as your heat exchanger.

[terpjr]

you are correct idahohay.
We have an open, non pressurized system from the OWB to plate heat exchanger in the basement and then our interior zones are pressurized to baseboard radiators.
My question was how to size the plate heat exchanger and if anyone had advice for brand, etc...
Thanks.

[ITO]

Mine is an SEC 20 plate, it is 9 years old and no complaints. I have a similar setup as mine is plate exchanger from OWB to pressurized indoor boiler system ( radiant floor heat ). When you mount it I would consider using a valve and hose bib on both supply and return from outdoor boiler, you can flush without removal and you can fill your outdoor system from a garden hose inside.
http://www.brazedplate.com/index.html

[willieG]

in the set up described, i dont think you could have too big of a plate exchanger... if all you heat with is the base boards you could add up the  out put of them and get a plate to match or exceed that. most single tube 3/4 basbaords are calculated to be around 600 btu per foot output at 180 degree water delivery. so a 10 foot baseboard would require 6000 btu delivery to maintain the 20 degree delta.

[terpjr]

So,
by my count, I have a 50 plate exchanger in my basement...
which, according to willieG's numbers, is the correct size...it is adequately heating my home.
However,
my OWB is firing up a little too often for my taste...i understand it takes heat to heat a house...
what would upping it to a 70 plate exchanger do?  would that bring more hot water to the radiator system with less heat loss?  would that make me more efficient so I burn less wood? 
If more plates are good...is there a way to link two together?  Also, I have hard water...will corrosion and deposits afffect my efficiency? 
Also, ITO , your idea to add the valves and hose bib...great idea...I will look at add that in the future.

[idahohay]

terpjr, just thinking out loud about your setup. This is all pretty much theory since nothing has been said about actual amount of heat to be transferred (other than 3000 sq.ft) your actual circulators and flow rates on each side of your FPHE, etc.  Since you are using baseboards, close approach temperatures are o.k. and by upping the amount of plates you end up with lower pumping resistance, enabling your circulator to move more GPM on the boiler side.  Again, no mention of the actual flow rates of your individual zones but lets assume you might need 50,000 btu/hr and your zones get 5 gal/min. You very well could be suppling 15 gpm on the boiler side which would help keep load side temp. high.

 To my way of thinking this would work fine but there is a reason the manufacturers rate the units as they do. Without a certain amount of turbulence the self cleaning properties of a FPHE disappear so more chance for build up. A 70 plate might get you a closer approach temperature(you might get more gpm out of your circulator)but at greater expense and shorter life. If you have any trouble heating your house, maybe a higher head circulator would work. I just looked at a 50 plate that was rated at 500,000 btu/hr, and a 70 plate that was rated at 825,000 btu/hr. (definitely overkill since the mfg. claims best efficiency at 84.5 gal/min)

Another thought is that none of this would affect your wood consumption only your delta "T's".

Hoping to learn something here so will stay tuned.