Need help tweeking a Knight WHN

Andy_27

Hi,
My new house(new construction) has a Knight WHN boiler with baseboard radiators.

During the last cold snap it had a little trouble keeping up in one room. What would be the best was to increase the water temp a little under these conditions.
1. Use the boost parameter
2. Use the shift reset curve parameter
3. Another parameter I have overlooked

Also - the heating contractor used a G. Alpha pump set to Auto Adapt mode in the secondary loop. When I questioned him about this he said the factory rep OK this and it would work just fine. Could I be getting too low a flow ?

This is a four zone system using zone valves with an indirect DHW set for priory.

Thanks

Ironman

Are you using setback on your thermostat(s)?

Andy_27

No - Thermostats are simple Honeywell T8775A's

Ironman

Boost is designed to help compensate for using setback. Something that should not be done with a mod/con.
The reset curve, along with other parameters, is really not something that a HO should be adjusting unless he's had some instruction on it. Nevertheless, if you know how to do it, I'd shift it about 10* higher to start with.
You could also try closing some of the dampers on the BBs that are closer to the stat.

SWEI

Does the cold room have a lot of windows? Were all the other rooms comfortable at the time? Is this baseboard series-looped?

Eric_32

What size boiler (model) and what size house? I prefer the ramp delay over the boot temp parameter if a multi zone house.... We have put in dozens this year..

Andy_27

The cold room is the master bed/bath. Its on the North end of the house (also has the longest run from the boiler). The boiler is a WHN-110. The house is 3500 sqft. 2x6 construction, raised ranch. Part of the issue (I think) is that a kick space heater was used in the master bath. It only activates when the master has been calling for heat for a long time. I plan on getting a low temp aquastat for it.

I hadn't considered tweeking the ramp delay.

Andy

SWEI

Is the master suite on its own zone? What about the rooms with southern exposure? Longest run from the boiler is a huge deal if the baseboard is series piped. I'd look at splitting the loop if that were the case. A direct return system can also have impaired flow to its furthest emitters. An inexpensive IR thermometer and some black electrical tape can tell you a lot in about an hour. The fact that you're on a raised foundation gives you some options to remedy the imbalance.

Andy_27

Master suite is on it own zone as are the rooms with the southern exposure. The baseboard is series piped within each zone. The IR thermometer (and readings) are now in the debugging plan.
Splitting the loop would mean tearing down ceiling drywall on finished lower level so I am trying to avoid it.

Thanks
Andy

SWEI

The small series loops created by your zoning should negate most of the rationale for splitting loops. I'm still curious what the supply and return temps are in that zone as compared with the others.

What kind of baseboard is this? You might look at changing some of it to a higher output design of the same length, which should require minimal finish disturbance.

SWEI

You could also try running the master suite on a separate reset curve.

Ironman

Andy said:

The cold room is the master bed/bath. Its on the North end of the house (also has the longest run from the boiler). The boiler is a WHN-110. The house is 3500 sqft. 2x6 construction, raised ranch. Part of the issue (I think) is that a kick space heater was used in the master bath. It only activates when the master has been calling for heat for a long time. I plan on getting a low temp aquastat for it.

I hadn't considered tweeking the ramp delay.

Andy

You need to order a low temp aquastat for the toe kick heater. This is your problem, not the boiler. The toe kick comes from the factory with a high temp aquastat that doesn't kick in until about 130*. The low temp stat kicks in at 110*.

I just had to do this on two of them we installed. I do it on all of them now.

Zman

These are all goods points.
I would also suggest trying different settings on the Alpha. I have not had great experiences with "auto adapt" You might see how it works in constant pressure 2 or 3.
Carl