Boiler Control Addition?


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Old 03-28-09, 08:29 AM
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Boiler Control Addition?

I want to add a new baseboard radiant zone to my proposed basement addition. My current system is a 2-zone hydro-air system with a 4 year old Buderus G-215 boiler with domestic hot water.
I have an Invesys Erie WA300 2-zone hydro-air boiler control for the current system. I am thinking of adding another Taco cartridge circulator to the header for the new basement zone but don't know what boiler control or relay to use (add) for the new radiant only system. Help?
 
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Old 03-28-09, 08:49 AM
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Just so I'm clear... you said "baseboard radiant" ... that confuzzles me... I think of radiant as tubing embedded in a slab, and baseboard as the fin tube stuff around the perimeter of the area...

Which do you want?

If you are indeed using radiant, you will need some additional equipment to control the water temperature in the slab.

I believe you are adding a fin tube baseboard run though, is that correct?
 
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Old 03-28-09, 09:04 AM
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I want to add a fin tube baseboard zone.
The boiler also has an L8148A Aquastat connected to the hydroair controller. The controller literature says you can add another Erie WA300 to make it 4 zone but the basement zone I want to add will not have another air handler (perhaps you leave those slots empty?).
 
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Old 03-28-09, 09:16 AM
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I think this is what you need to do... one thing to mention is that you probably want to use a pump with the internal flow check valve, or use an external one. You don't want flow induced in the new loop when the others are running.



I'm pretty sure you don't need the expense of another wa panel, the Honeywell R8845 relay can be had for a little over $50 ... check Patriot Supply - R8845U
 
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Old 03-28-09, 10:19 AM
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Thanks NJ Trooper!!! I was thinking a simple relay add on would do. Couple of follow-up questions..
I wonder if there is a similar product that will allow me to connect the Hot Water Temperature Controller (hot water priority aquastat) on the WA300 to the new relay?
When you say Pump and check, I think you mean I can use the same Taco cartridge recirculator (Model 007-F5) and Taco 219 Swetchek (check valve) arrangement I have for my current zones?

It's interesting that current control doesn't have anything connected to the Boiler/Burner Control.
 
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Old 03-28-09, 11:22 AM
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I was afraid you were gonna ask about priority on the HW heater!

I'm sure there's a way... I need to look at that some more... but later on... in the meantime, please describe your system more fully. Apparently you do have an indirect water heater... anything else that might factor in?

Yes, the pump and an external check valve is fine, Taco (and others) do also make pumps that have the check valve built in. It does sometimes happen that they can be problematic... if they are installed such that they are pumping UP, air can collect around the impeller, and the pump won't pump, and can in fact burn itself out...

It's interesting that current control doesn't have anything connected to the Boiler/Burner Control.
Eh? What is connected to the 'T T' terminals on the 8148 aquastat?

Also, if you haven't already done so, it might not be a bad idea to do a heat loss calculation on the area that you are heating. Doing so will allow you to only install as much baseboard as you need, and save some $$$.
 
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Old 03-28-09, 12:03 PM
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More description of the system....
Buderus G215-4 oil boiler with Riello 40 burner,
L8148A Aquastat (burner is connected and TT terminals are connected together, nothing connected to circulator terminals) WA300 2-zone hydro-air boiler control (water aquastat and 2 zone thermostats connected as well as water and 2 zone circulaotrs/pumps, and the basement and atttic air handlers).

The boiler heats the Vaughn 70 gal domestic hot water. The 1-1/4-in black pipe header splits upward to the three pumps and 3/4-in copper lines (water, and 2 heat coils/zones) each with check valves and lots of isolation ball valves.
Have not started htis project yet and am trying to see if I can handle this. I want to add the baseboard zone without messing up the current system. Good idea about doing the calcs for sizing...another research project for me.
 
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Old 03-28-09, 04:54 PM
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TT terminals are connected together
...and this means that the boiler is being called for heat 24/7, and stays within the differential range of whatever the 8148 temp setting is at... and you are probably using an awful lot of oil to do that...

Were you living in the home when the system was installed? If so, was there any explanation as to why it was set up that way?

I don't know a heckuva lot about hydro-air... I'm thinking that the reason the boiler is being kept warm is so that when there is a call for heat it doesn't blow cold air for several minutes before hot water is pumped to the coils... sounds logical, right? Still, it would make more sense to me if there were additional control that on the air handlers that would hold the blowers off until the water was hot. This could be accomplished with an aquastat at the air handler. I do notice that your WA panel does have either a 90 or 180 second delay for the fan control. This may be for that reason also...

Is your system combined with a central AC unit?

If you wish to continue to run the system in this fashion with no other changes, then simply ignore the TT wiring in the previous diagram. You can also get by with a simpler relay... but you may wish to use that one anyway, in case you want to make some changes in the future and save some $$$ on oil. A different relay won't really be any cheaper.

As for the priority on the WH... since the boiler is being kept hot all the time, I doubt that the added baseboard run will have much impact on recovery time if it happens to call during a DHW call. I would try it and see how it performs first.
 
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Old 03-29-09, 06:41 AM
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Yes, the boiler is always hot between 170 and 190 deg F 8148 aquastat settings. Probably why my mech. rep sent me a proposal letter to install a Tekmar 256 modulating contoller (for $835).

This is a new home system in 2004 and yes there are two AC condensers.

I think you are right about why they set the system up the way they did (not wanting to blow cold air in the 3500 sf house with lots of heat and DHW demands). You now have me thinking I need the modulating controller (Tekmar 256 or equal) and the extra boiler control for the added basement baseboard zone.
 
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Old 03-29-09, 08:40 AM
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I think the reasone they sent a proposal to intall that 256 was for their revenue, not yours.

I don't believe the 256 is going to 'solve' anything.

My opinion is that a solution that precludes keeping the boiler hot 24/7 will be MUCH more worthwhile.

How much do you think the 256 will be allowed to drop the temperature before you start 'feeling' cold drafts in the home when the heat kicks on? That's one of the perceived problems with hot air... even though there may be 140 water in the coil, by the time that air starts blowing around, it may 'feel' like a cold draft. Also, the water returning to the boiler must not be allowed to be too cool. There's likely a fairly large difference in temp (Delta T) between the supply to the coil and the return to the boiler. If you allow that return water to approach much under say 130 for any length of time, the flue gases will start condensing in the boiler and in the flue pipe, and that condensate is ACIDIC, and WILL destroy the boiler in much shorter time than it's expected life.

I would think long and hard before I dropped almost 1K on a setback controller on your system.

Currently, the system heats the home just fine, correct? So there's no problem there that needs the 256...

Using a lot of oil? I'm sure you are... but the minimal amount that the 256 should be allowed to setback the boiler temperature is not going to save much, and may introduce the problems above... worth it? I don't think so.

extra boiler control for the added basement baseboard zone.
Which extra control are you talking about here?

Myself... I would explore the solution I mentioned earlier... possibly converting to a 'cold start' boiler, and implementing a control scheme to hold the air handler blowers off until the water was hot enough... and this could likely be done cheaper than adding the 256... even if the same price, it would save a heckuva lot more $$$ in oil.

What model air handlers are in the home?
 
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Old 03-29-09, 06:59 PM
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Basement air handler is FB4ANF030 Bryant (although it has a Carrier plate on it) link is to a photo of it. I beleive basement is 2.5 tone air handler.
Certified A/C & Plumbing Service
Attic is 3.5 ton Bryant FB4BNF042. Condensers are both Bryant.

Good point about the modulating control. I suppose they would put it in and then set it with a high minimum temperature because of the concerns you stated...as you said then what's the point in having it.

My annual oil consumption is 1100 gallons per year. Don't know if there is a solution that avoids keeping the boiler hot except for removing the hot water from it and I don't want to do that. These Buderus boilers are insulated well and hold their temperature much better than older boilers.

I there was a cold start scenario would I have the temperature problems you noted or is the idea to hold off on the air handler heat demand until it heats up?
 
 

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