Hydro-Air Problem

Ted P.

I would say that the first thing to check would be your stat to see if you can delay your fan from coming on fast and delay it more.
Second i would get a fan limit control that would control your fan according to the temp. of the coil so you don't get the cold drafts when the fan comes on.
Ted

TomMcc

Hydro-Air Problem

My parents have an older house, which originally had radiant heat. Due to some leak issues several years back, a contractor converted the house over to a hydro-air system. I've been spenting some time at the house and I believe the system is not working properly. The problem as I see it is that fan comes on prior to the heat exchanger getting hot water from the boiler. That results in cool air being blown through the house. My questions are:
1. What is the relationship between the thermostat, the fan control and the circulator control?
2. Is there an adjustment that can be made?

Any other information would be helpful!

Regards,
Tom

TomMcc

I forgot to mention that the boiler was recently equipped with the Beckett Heat Manager device. Not sure if this has any effect or not.

chris_95

what we do for the hydro air system is put a strap on aquastat on the return line of hot water by the air handler(blower). The aquastat will be wired into your fan so that the fan comes on when the water temperature reaches about 140 degrees. This will make sure you do not get the cold draft when your heat turns on.

Jed_2

Some

Air handlers have a time delay built in to the control circuit, others require a strap-on aqaustat to call the blower. What do you have on the air handler?

Jed

Mike T., Swampeast MO

I'll get flack for this, but the actual problem is hydro-air.

Senseless in most residential applications. You have all of the problems of forced air with none of the benefits of true hydronics.

Let me guess... They used the existing boiler to power the hydro-air.

[Deleted User]

Sounds like a control issue...

EVERYWHERE...

At the heat source, if the reset control takes the water much lower than 160 degrees, you can expect to feel a sensation of cool air and draftiness. As others have said, it is a convective system, and is a whole different beast than say a radiant system.

If'n it were me, I'd check the minimum operating temps, add a thermal fan switch (strap on low limit) and avoid any set back themostats. The MRT gets pretty low with F.A. systems, and makes the human occuants even cooler...

Go radiant. Walls, floors, ceilings, windows, counter tops, fire place mantle's, fire place hearths, old pot bellied boilers, benches, bed frames, desks, chandilere's, bench's, concrete dogs.... All (at least 60%) radiant :-)

Radiant rules, literally.

ME

[Deleted User]

Howsabout this logic...

Nearly continuous air circulation, operated on a variable speed, connected to a non electric thermostat. The pump is a fixed speed pump. The fan is "watching" the pressure differential across teh TRV valve. High differential = minimal demand, fan goes to lowest speed. As room cools, valve open, decreases delta P, causing fan motor to increase its speed, thereby delivery more, even btu's.

A person would still have to think twice about camping out under a supply air duct, but it could work...

Or go total solids state electronics, and control the fan speed and the pump speed according to a differential between set point and actual room temperature.

Has any one ever wired two pumps into one VS control circuit, like on a tekmar control for example?

What would you expect to happen...

ME

Unknown

Fan delay relay

I've always liked this route better, I'm not sure why. To each his own I guess.

Mike T., Swampeast MO

Your logic is fine Mark.

The problem is the ductwork. What's needed is extremely well sealed work with fully ducted returns to each and every room and all ducts insulated and in conditioned (or at least basement) space. When is that going to happen? Maybe in the finest new construction and under direction of a well-informed architect, but in a forced air residential retrofit? Need I even mention the physical impossibility of balancing the size of the returns to the supplies when the system delivers both heated and cooled air?

HydroAirJoe

Could be a simple problem with your thermostat. Does your thermostat have a e-f (pich F for fuel) switch or if it's a programmable thermostat, there is usally a setting wich is fan is turned on when a call for heat is made or furance controls fan operation. Pick the latter. I had the same problem.
I have 2 different types of airhandlers on my Hydro-Air system and they both have a 45 second delay before they turn the fan on. When the stat is satisfied, they have an addtional 20 second delay before they turn off the fan. Also you are always going to get a cold blast from the supply when the fan first kicks in due to the cold air in the ducts. Varibale speed airhandlers will reduce this problem.

zeke

Don't they have tstats that can do this time delay function?
If not, how expensive is adding the TDR, and how?
I have this problem as well and think the clamp-on aquastat solution is too expensive.
Would apprciate your input.