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[netwerx-r-us]

I'm building my own heater for my greenhouse  , 22x22 water to air exchanger , 2o inch fan 3150 cfm and I bought a Honeywell RLV3120A1005/H Digital Non-Programmable Thermostat for Electric Baseboard Heating to turn the fan on and off as needed, i bought this because it was 110 volts not 24 , looking in the book it says not compatible with a fan forced heating system ( didn't say that in the description on amazon ) also says heating cycle length , 15 seconds,

so the question is did i buy the wrong thermostat

here it is on amazon http://www.amazon.com/dp/B002Z7EBBU/ref=pe_175190_21431760_M3T1_SC_dp_f1

thanks ahead of time

[RSI]

It doesn't just turn on and off, it pulses the power so the baseboard puts out less heat so it can hold the room temp more even.
TRIAC switching for accurate temperature control of +/-0.5°F.
If you don't care about possibly killing the fan or thermostat, I would give it a try. It may give you a variable speed fan or might not work at all.

Using a fan center relay and a 24v thermostat is probably the best way to do it though.

[dwneast77]

I agee with RSI, I have 5 blowers set up with fan center relay and 24v thermostat and works great!!

[netwerx-r-us]

how about this one,?  I just need it to turn the fan on and off as it calls for heat , probably a bit cheaper than a 20.00 24 volt thermostat  and fan relay, will it work just as well ?



 http://www.amazon.com/Lux-Heating-Cooling-Programmable-Thermostat/dp/B000E7NYY8/ref=pd_rhf_cr_p_t_1

now I just need to figure out what to do with this one, probably cost me more to return it than its worth


thanks in advance

[dwneast77]

This may work to control the fan, but I see another problem.  With your proposed setup it sounds like you would have hot water running through your radiator all the time?  If that is the case, I can tell you from experience that you will have a LOT of wasted heat.  Won't be a problem on a cold night, but certainly during the day all the natural convection of heat would need to be vented out and wasted.  I know this as I own and operate with my parents a greenhouse business and I am running 4 greenhouses and my home off of 2 OWB's.

The best and much more efficient way to supply water to the radiator is to have the pump push the water to a 3-way zone valve at the radiator.  You tie that into a fan center relay and control it with the 24v thermostat.  It works very slick.  I'm running 5 of these setups.  If you want to see pics let me know I'll get you some.



Side note:  The first night I started my boiler when it was new, I did not have my wiring finished at the furnace so I left my zone valve open with the manual open lever to let water flow through the radiator overnight.  The natural convection through my duct work heated my house up well over 80 degrees.  It was an incredible waste of heat.  I'd just like to save you the extra work later.  Only other way around it that I can see is to set up a louver or some sort to stop natural convection but something that the blower can push open.  But that unit is still going to stay very hot and waste a  lot of heat.

[netwerx-r-us]

definately throw in some pics, I appreciate the input , you make a very good point , seems like i learn most things the hard way and if i can learn form someone else who already did t I'm better off , as this is my main greenhouse 30x50 and adding another 20 x 50 soon i don't think wasted heat is a good idea, i went this route so i wouldnt have to get up at 2: 00 am and walk to the greenhouse and fill with wood

thank you ,

P.S where are your greenhouses and what do you grow , my wife is always looking for new plants

[netwerx-r-us]

what you are saying makes absolute sense but it brings up another question , will i run into the same problem when putting my water to air exchanger into my existing ductwork for my heatpump? , seems like it would as how water will be running through this also unless its wired in some way to be "on demand" turning on the pump at the OWB when needed , this changes things a bit but very good to know

thanks

[dwneast77]

Yes, this setup would be "on demand".  You will have a pump running 24/7 from the boiler and through the furnace loop.  But by using a 3-way zone valve the hot water bypasses the HX until there is a call for heat.  When the thermostat calls for heat, the Fan Center Relay opens the 3-way zone valve 5-10 seconds before kicking the blower on.  This gives the HX time to warm up before the blower comes on giving you warm air right from the get go and it is consistent.  No cool down cycles like with oil fired furnaces.

Pic 2479 shows HX setup with bypass water line to the 3-way zone valve and back to the boiler.
Pic 2480 is the Fan Center Relay.

It is a very easy setup to wire in.  I followed diagrams on centeralboiler.com,  they show many different setups.  I've not seen any other boiler sites offer so much setup info. 

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[RSI]

Almost everyone just lets the water always circulate through the heat exchanger. Some houses do heat up a lot worse than others depending on how the ductwork is layed out.

A lot of people like the natural convection too with the reduced blower run times.

Also, 3 way zone valves are very restrictive.

[dwneast77]

RSI, I know from my experience that my home heated up well over 80 degrees the one night I had the 3-way zone valve manually opened and that was with an outside temp of around 40.  I start my boiler in October when there are still days in the 50's and even 60's.  I don't even want to think about the house getting any warmer than 80s.  I'm not comfortable at 75.  This is my 5th season running with this setup and I love it. 

My home is set up with 1" PEX supply and 1" zone valve and I get nice hot air at the register.  I have not actually put a thermometer to the register, but it is good hot air and my blower only runs a few minutes at a time, 5 at most in the cold weather.   In my greenhouses, all of my blowers are only set up with 3/4" PEX and 3-way zone valves.  My biggest greenhouse is 27'x72'.  In this house I run 2- 140k btu HX, 1 at each end.  My second biggest house is 21'x48' run with just 1 - 140k btu HX. 

My CB dealer is the one who put me onto this setup, though he probably would not have recommended 3/4" setup to my greenhouses.  I didnt' know any better, but it works pretty well.  Anyway, I'm glad he did.  I think it's a great setup.  And it's easy to do.

netewrx - It appears that your HX coil is equivelent to a 140k btu.  Depending on your climate and temp range, this may be a little light for your big house.  I would definitely recommend using 1" pex and zone valve.

My place is located in Maine.  We grow a wide variety of annuals mostly, a good selection of vegetables and some perennials and about 1k hanging baskets.  We have a total of 8 greenhouses, 4 running off of my 2 OWBs.

[RSI]

Like I said, some housed do heat up a lot worse than others. Most work fine with the water always circulating through the HX.

I prefer you use a pump on a secondary loop instead of a zone valve. It is a lot less restrictive.

[netwerx-r-us]

thank you all for your input ,It is invaluable to me ,  Im seeing that there are several different ways to achieve the same thing , each install is different and has different requirements

for the greenhouse I'm not as concerned with it running 24x7 as the heat will go into the greenhouse , its not per se wasted , it can heat up pretty good simply from the sun during the day so it may get a bit warm , another option that a fine gentleman Im'd me about was to also hook my pump  to the 110 volt thermostat inside the greenhouse  so the pump and fan come on together , as this is the only appliance on that line that seems like the best option , yes i will get cool air for about a minute and half but it wont be running 24x 7 and it will probably although minimal cut down on pump electricity usage 24 x 7 vs as needed

that brings me back to my house ex changer when i put it in in the next couple weeks , I plan on running a 20 plate plate and then to a 22x22 exchanger inside my duct work ,  my air handler is in the basement and i have 3 floors to contend with , when i built the house i went crazy and had 2x6 walls and blown in wall insulation for a r value of r23 , i guess the question is will it heat up to much from the  natural convection or do i need to look at a way to separate the 2 and have one on demand , definitely puts a kink in the budget to have to run separate  lines or install a zone valve , i wont be able to bring the pump inside on this one as it is higher elevation that the wood boiler unless i add a second pump inside the basement and wire it on demand , stealing a line from Scott , " this is making my head hurt "

thank you all again , as stated your input is invaluable to me

[dwneast77]

The idea of using the line voltage T-stat for the pump in the greenhouse is a good one I think, esp. if your boiler is not too far away.  In my case, I have 2 long runs to 2 of my gh blowers.  Before I set up the blower system, I tried my first season using baseboard fin tubes lined under my benches down each side of the greenhouses.  First off, I only had about 1/2 of the fin tubes needed for the area in each house.  Other problem was that there was all that cold water in the lines all rushing back to the boiler at about the same time (within minutes in the evening as the sun goes down) (don't forget I'm running 4 gh's) so my boiler water temp would drop like a rock.  Might not be so bad now that I have 2 boilers, but still.   That first year was a constant juggling act between my oil thermostats and the baseboard thermostats, trying to keep the oil burners t-stat close enough to just back up the baseboard t-stats and give each unit time to sit idle to help the OWB maintain itself.  I didn't sleep much that winter.  Wasn't much better the next 2 years even with the blowers.  Last year, having the second boiler gave me some peace of mind and allowed me some sleep.

With regard to the home line, understand I'm not trying to just spend your money for you.  Try not to overthink things.  I know it's another $175 or so for a 1" zone valve.  But I'm of the mind to do something once, know that it's going to work correctly and not have to think about it.  Through much of the winter, it may not be a problem at all to allow the natural convection.  But when the temps start to rise again in the spring and also during the early part of the heating season, the house may warm up substantially. 

Another thought to maybe slow down the natural convection I guess.  You could use another line voltage thermostat and tie that into that pump as well, like the gh line???  There will be some "ghost flow" of the boiler water through that line unless you were to put a regular zone valve with that pump.  Same will happen with the greenhouse line.   Oh wait,  I guess that is not going to work here since you are running through the plate exchanger.  You only need the one supply and return line to the house.  You can add the zone valve later if you want.  See how things work in your house and go from there.  But don't over think it.  We all have a budget to work with.  Mine is certainly pretty tight nowadays.    Good luck.  Keep us all posted!!