1 Year old house Navien Ncb 210e boiler issue

[Drockalisty]

Hi all, Im looking for advise on my new house/ boiler. Our house is just over 2300 sq ft 3 bedroom/2.5 bath/ office with vaulted ceilings in the master bedroom and great room. We have radiant infloor heat thru out the house. Originally we had 3 zones (thermostats) in the house. One downstairs in the great room, hallway upstairs and master bedroom. I thought we were getting a thermostat in each bedroom so each person could control their out temperature. One of the bedrooms was always colder than the rest. I was told if I adjusted the flow meters to the rooms that room would get warmer. I tried that. Didn't work. So I decided I would install a thermostat in the other 2 bedrooms, run the thermostat wires and hook them up to their own actuators to see if that changed anything. Seems like the helped the bedroom that was always the coldest. Now my problem is its been a constant -2 - 10deg f outside the last week or so. I can't seem to get the house temp above 63-65deg f. Luckily we had a woodstove put in when we had the house built. I don't know how the plumber programed the boiler when he installed it, but it doesn't make sense to me that it can't get the house up to temp which the thermostats are set at 68-69deg f.. I had the thermostats cranked up to 75degs for about 12 hours trying to see if the house would get any warmer but that didn't work. I took off the panel that covers the manifolds for both downstairs and upstairs, both showed 130 degs for the incoming and the return was around 120 degrees...Looking at the boiler when it's on it will show 150 degrees when firing up I'm guessing. I don't know much about boilers, but found this site and some forums of other people having problems getting their naviens dialed in. All the forums I saw were baseboard related and not in floor radiant heat. Reason why Im writing this one. Anyways any help would be appreciated! Thanks

 

[Dana]

You're probably radiation-limited at the 150F water temperature, but you can bump that puppy up t0 180F if need be, and

Do you have the outdoor reset control? Is it enabled?

Read and understand the manual. The parameters section start on p56, the outdoor reset discussion on p80. You'll most likely have to set up a custom reset curve to make it work, but you might just set it for the default cast iron baseboard or fin-tube settings, and see if that gets you through the cold stretches, and dial in a custom curve later.

 

[Sponsor]

 

[Drockalisty]

You're probably radiation-limited at the 150F water temperature, but you can bump that puppy up t0 180F if need be, and

Do you have the outdoor reset control? Is it enabled?

Read and understand the manual. The parameters section start on p56, the outdoor reset discussion on p80. You'll most likely have to set up a custom reset curve to make it work, but you might just set it for the default cast iron baseboard or fin-tube settings, and see if that gets you through the cold stretches, and dial in a custom curve later.

It doesn’t look like the plumber installed the outdoor reset control.... If I don’t have that am I sol on making this thing work in the cold temps?

 

[Dana]

Not at all- you can just set it up for a higher fixed temperature. The outdoor reset is useful for getting the last 5% of efficiency out of the system and can also increase general comfort levels due to very stable room tempertures when you get the curve tweaked in. It may be worth installing the outdoor sensor and doing that, but for now just turn up the temperature.

Read section 7 in the manual on what the DIP switch settings mean (so that you know what mode it's operating in) and section 10 on how to adjust the temperatures. Make sure that parameter G is set to "-" (outdoor reset not in use), which will allow you to run a fixed setpoint temperature on either the output or return water temperature (depending on what mode it's operating in.)

 

[Zl700]

Seriously?
Your telling him to turn it up to 180 degrees with in-floor radiant heat?
How about asking about tube size, spacing, flow rate, floor type and surface temps?

 

[Dana]

Seriously! He doesn't know the answer to those questions and probably can't easily find out, but he knows it's not keeping up with the load.

Short of a complete re-design of the system, turning up the temperature. It probably doesn't need 180F, but if it needs it, the boiler can deliver it. Bumping it up 10F at a time is more conservative than going full-on to the boiler's max. If I understood him correctly the boiler hits 150F during a call for and still isn't cutting it.

 

[Zl700]

Seriously! He doesn't know the answer to those questions and probably can't easily find out, but he knows it's not keeping up with the load.

Short of a complete re-design of the system, turning up the temperature. It probably doesn't need 180F, but if it needs it, the boiler can deliver it. Bumping it up 10F at a time is more conservative than going full-on to the boiler's max. If I understood him correctly the boiler hits 150F during a call for and still isn't cutting it.

Perhaps you don’t understand radiant floors. We don’t even know the surface type but exceeding 85 degree floor temps can damage hardwoods. Besides being uncomfortable. A heat loss is required along with radiant design and knowledge first. He mentioned cathedral ceilings. Perhaps tube size, flow rate and spacing isn’t sufficient or heat loss exceeds room requirements. Often times these situations require supplemental heat often done with a fan coil or second stage heat on the AC unit.

Turning boiler to 180? Is it a slab, staple up, floating, track, what? New house, first cold winter, somethings missing. Try taking a floor temp, that will tell a lot

But 180 degrees? Potentially a 110 degree floor? Come on man this is not a baseboard house.

 

[Drockalisty]

Almost All the pex tubing is 1/2”. One room which is the furthest from the manifolds is 5/8”. As far as floor type, I have tile in the kitchen, entrance and bathrooms. Carpet in all the bedrooms and hallway upstairs. And quick lock pergo laminate/wood downstairs in great room, office, and dining room. I have 3/4” subfloor and the tubing is ran in between each floor joist. Stapled up and has a heat shield paper to radiate the heat thru the floor. I believe most of the joists are 16” on center. All the flow meters are around .6 - .8 gpm. What do you mean by surface temps? Using a IR camera or heat gun to see how warm the floors are when the boiler is running?

 

[Drockalisty]

The .6 - .8 flow rate is the max they will flow too. The flow meters are fully open.

 

[Dana]

But 180 degrees? Potentially a 110 degree floor? Come on man this is not a baseboard house.

With a 110 F floor it would keep up with the load at -50F outside with some windows open. I'm really NOT worried about that actually happening. The thermostat will be satisfied well before that happens.

The whole 180F water damaging hardwood floors issue is BS- never happens in the real world. MANY radiant floor with hardwood in the upper midwest using extruded heat spreaders hit 180F EWT on their reset curves when outdoor temps are well into negative double digits, without damaging the floors.

In Juneau it would be well worth adding outdoor reset control if it's taking 150F+ water to cover the load when it's actually cold out. Juneau has 12 months of heating season, but most of the time it's pretty mild, and would be able to run at a lower, higher efficiency condensing temperature most of the time.

If it's a simple staple-up with no heat spreaders, and only shiny-sheets for insulation it might actually need 180F water, and it won't be a problem for the floors. Raising the temp by 10-20F from wherever it is now will probably "fix" it for the time being, but it's also worth adding:

1> Stamped sheet metal heat spreaders, of the type that grips the tubing rather than simply overlaying it.

2> Batt insulation (R13 if it's over a warm, conditioned basement, R30 or whatever will fit if it's over a cold basement with no foundation insulation) , snugged up to the sheet metal heat spreaders.

The heat spreaders will improve the heat transfer from tubing to subfloor, allowing lower operating temperature, the insulation will reduce the heat loss to the space below. The simple radiant-barrier is a pretty crummy substitute, and the space between the RB & subfloor is all too often an unimpeded thermal bypass for any air leakage at the band joists (which should be caulked tight with polyurethane caulk &/or can-foam anyway.)