NEED ADVICE on Adding Hydro Air Zones
Help! I am getting all kinds of opinions on how to add additional zones to our oil-fired Energy Kinetics boiler. Seven years ago, we installed a boiler that is 2x the size we needed (in anticipation of our addition). One air handler and an in-direct hot water maker ran off a single circulator. Both of them ran very hot (air too hot, water too hot), even though we reduced the boiler temperature.
The question: in adding 2 additional hydro-air zones, should we still run everything off of the single circulator? My understanding is that if every loop has its own circulator, we have much more control over the temperature of the water going to that zone.
My HVAC guy is not recommending it, and wants to charge an additional $3,000 to put pumps on each zone.
Thoughts?? Need to make a decision quickly – all pipes and air handlers are in.
Replies
Hmmmmmm systems "too hot" well most boilers run at 180 degrees hot water maker should have it's own thermostat that controls a pump or solenoid valve. As far as controlling new zones doesn't matter if it's a pump or a solenoid valve a thermostat controls them. If using pumps then you don't have to balance the system if your'e using valves on a single circ line then you need balancing valves & balance the system hope this helps.
Here is what I'd do: Call up Rob at NRTradiant or Siggy at HydronicPros and have them come up with a proper layout for your system. They'll acount for the capabilities of the circulators, zone valves, etc. That way, you can minimize the number of circulators and hence installation cost.
From the little you have posted, I suspect that the oil boiler is either not properly piped or set up. High air/water temperatures in a hydro-air system can be a symptom of a boiler that has not been piped primary-secondary. Presumably, the hydro-air coils are also not getting mixed water (either via a 4-way valve or injection mixing) or they'd be producing more comfortable heat, particularly when couple with an outdoor-reset control.
So, what does the piping look like? Do you have a proper primary-secondary setup? Outdoor Reset Control?
Thanks! I visited both sites. It looks like advice I could have used well in advance of implementation of the job. Honestly, I believe that my contractor has done a good job with each zone and its components, but I have concerns that he doesn't know what he is doing when it comes to controlling the zones and boiler. So much of the system is already in (pipes to air handlers, ductwork, returns). Is it possible to actually hire someone to come and evaluate what has been done, and what should be changed?
I guess ultimately I need to find out if there is a way to get the control we need without putting circulators on every zone. If this is the way to go, I should make that decision now, before all of the zones are connected to the boiler.
My other concern is my contractor's decision to put an antifreeze solution directly in the boiler water. I have heard that this is not good for the boiler. In coastal CT, I am wondering if it is OK to just run plain water to all of the zones? The pipes, air handlers and ductwork are all in insulated, semi-conditioned space.
Thanks again for your feedback.
This is one of four variation that could be used.
The key to this particular schematic is:
1) Indoor/Outdoor Controller on boiler w/ DHW Priority.
2) All zone valves on the fan/coils must be equal percentage types fitted with modulating actuators controlled by modulating signal thermostats.
3) There must be a spring loaded bypass valve installed.
This is called a variable temperature variable flow system and works great when you follow the criteria...take a short cut by using low cost quick opening on/off valves and you may as well forget comfort...it must use all three criteria.
The other variations include zoned circulators, primary/secondary or reverse return piped systems...and a few others - but all roads lead to Rome as they say.
The benifit of a good quality control valve (as opposed to a cheap zone valve) is the flow/output on a fan/coil can be lineralized...i.e.: 50% flow = 50% output which really improves the comfort. This is not possible with the typical off the shelf zone valve. The good guys can also be manually operated in a pinch.
Pipe in a spare circulator and voila...you have a system very close to what I call designed for failure...i.e. when (not if) something screws up you can still move water through the system zones.
As far as glycol...only if there is risk of freezing in the coils...and this could happen if the duct design includes introducing outdoor air for make up on the ventilation system. If the water temperature and flow is adjusted properly with the indoor/outdoor control, the valves will modulate open so there would constant flow during cold weather... it's in the event that you have a power or fuel failure which creates the concern...so what are the chances of fuel or power or both failing?
As I said, the schematic below is one of four variation that could be used.
I don't have a preference and neither do the water molecules...
http://wonderfulwombs.typepad.com/./photos/uncategorized/fan_coils_2.JPG
RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com
Edited 9/26/2005 10:03 pm ET by RBean
Edited 9/26/2005 10:04 pm ET by RBean