Lochinvar WHN055 Panel Rad Install, First Fire Qs

bmwpowere36m3

Hey guys, its been a while… I installed a Lochinvar WHN055 earlier this year and more recently the Buderus panel rads (ordered in Jan/Feb and received Sept, don't ask lol). Anyway, the gas company installed the meter today and we fired up the system for its virgin run.



I disabled the ODR and set the supply temp to 180* (to heat quicker), outside temp ~45-35* and the indoor temp rose from 50* to 60* in about 1.5 hrs. I let the system run for two hours and drained/refilled the system.

So here are some parameters of it running (currently after draining):
ODT 30*
IDT 56*
Boiler Supply Temp 163* (System Temp with 1-2*)
Boiler Inlet Temp 147*
System Return Temp 120*

Boiler Pump (Grundfos Alpha), Spd I, 3 GPM, 7 watts
System Pump (Grundfos Alpha), Spd III, 2 GPM, 43 watts



What's interesting is on the system side (3 panel rads off 6-circuit manifold) with the pump maxed out (Spd III), I'm only getting 2 GPM. The flow meters indicate two rads with 0.5 GPM and one with 1 GPM. The 1 GPM rad is a short run (10')… I plumbed the radiators with Roth 3/8" PEX (homerun), which I'm starting to think was a mistake. The longest run is ~90' (total). I still was planning on added 3 circuits (towel warmer, small radiant staple up, another panel rad).

The flow setter on the rads are fully open, no thermostatic heads installed (yet). Otherwise, the unit is pretty quite… all you hear is the fan running, especially at 100%. Don't even know it lights off, besides a very faint change in sound and then the fan, haha.

Gordy

Have you tried changing pump speeds on system side. Also the gpm read out on the alphas are not exactly accurate. There is little consequence of running larger diameter tubing. Over pumping also applies to trying to achieve flow rates through smaller diameter tubing with bigger circ.

In your case do you need 1gpm to the rad? Think carefully, and apply the universal hydronic formula.

Gordy

Also take note of boiler delta. Also system side verses boiler side flow rates.

Paul48

It seems a shame to not take advantage of this boilers ability to control the speed of the boiler pump. Paired with a DT circ on the secondary side and you'd really have something. The way it is, a third of the heat produced never sees the system.

Ironman

Under average, normal conditions, the factory settings on the Rad's flow setters are ideal for producing their desired Delta T. 3/8 tubing will result in slightly less flow on a longer run, but like Gordy said: think universal hydronics formula. 1 GPM @ a 20* Delta T = 10k btus; at a 30* Delta T, it's 15k btus. I doubt that any of your rads are sized for that much output.

That boiler has parameters for ramping the firing rate and minimum run times to prevent short cycling. I would highly suggest setting them up as that can be an issue once your TRVs and ODR are installed.

Gordy

I would suggest getting the ODR set up, and parameters programmed now.

Gordy

What this comes down to is system side is less gpm than boiler side. The btus go back to the supplier. The boiler never likes inventory.

SWEI

Gordy said:

I would suggest getting the ODR set up, and parameters programmed now.

To do that, crank all the TRVs up to maximum and the thermostats up to 85°F and then start adjusting ODR parameters until the coldest room is comfortable. Then adjust the flow setters (radiator stops) on any warmer rooms to bring them down a bit. Now raise both ends of the reset curve by a few degrees and dial in the TRVs for each room.

bmwpowere36m3

Gordy said:

Have you tried changing pump speeds on system side. Also the gpm read out on the alphas are not exactly accurate. There is little consequence of running larger diameter tubing. Over pumping also applies to trying to achieve flow rates through smaller diameter tubing with bigger circ.

In your case do you need 1gpm to the rad? Think carefully, and apply the universal hydronic formula.

Yes, its on three now (constant speed). I can drop it to one, the flow meter on the loops barely registers and the circ displays zero GPM (though I can see fluttering on the flow meters, so its flowing).

No I don't need 1 GPM per rad… but based on head-loss calcs I should have more flow with the pump. Well, I was running a near 50* delta on the system side. It would have been nice to pump more and see how that runs (in the future). Which I can't since the system pump is MAXED out at speed III.

Remember I just fired up the system and I wanted was to heat the house quickly. That's why no ODR and high set point. Just HEAT!

bmwpowere36m3

Gordy said:

Also take note of boiler delta. Also system side verses boiler side flow rates.

Yes, I see that… but the boiler isn't short cycling, yet. The BTUs are still being transferred to the system side. It ran at 100% (output) for hours before I left the house for the night.

The boiler pump is on Speed I (so the slowest it'll go).

bmwpowere36m3

Paul48 said:

It seems a shame to not take advantage of this boilers ability to control the speed of the boiler pump. Paired with a DT circ on the secondary side and you'd really have something. The way it is, a third of the heat produced never sees the system.

My understanding is, a pump that the boiler can control is north of $500. Pls correct me if I'm wrong.

When I posed the question earlier about boiler pumps, if was either: use a variable-speed (boiler controlled) pump $$$ or a constant-speed pump $. No delta-P or delta-t (pump controlled).

Good thing I didn't use the included Grundfos 15-XX whatever pump with the boiler… that'd be over-pumping in a hurry. I actually used that for my DWH.

bmwpowere36m3

Ironman said:

Under average, normal conditions, the factory settings on the Rad's flow setters are ideal for producing their desired Delta T. 3/8 tubing will result in slightly less flow on a longer run, but like Gordy said: think universal hydronics formula. 1 GPM @ a 20* Delta T = 10k btus; at a 30* Delta T, it's 15k btus. I doubt that any of your rads are sized for that much output.



That boiler has parameters for ramping the firing rate and minimum run times to prevent short cycling. I would highly suggest setting them up as that can be an issue once your TRVs and ODR are installed.

I have two sets of "flow-setters", on the rads themselves (where the TRV mounts) and on the manifold for each loop. All the rads are set to "N" now (fully open) and as well the flow-setter/meters on the manifold.

I wanted to see the MAX flow capable for the system I "designed" and installed. My only concern is in the future I cannot bump the flow any higher. The alpha pump is nice with the delta-p for TRVs, but I believe it only comes in one "size" (15-55).

One step at a time, first "heat"… now I can "play" with the system (hooking OD sensor back up, ODR curve, ramp, boost, etc…).

bmwpowere36m3

I take a look today at the system, the house this morning was up to 70* (9 run hours and 27 cycles, but I played with it a bit when first fired up).

Paul48

The variable voltage circulators are expensive, but, then again, what isn't?

bmwpowere36m3

Paul48 said:

The variable voltage circulators are expensive, but, then again, what isn't?

True… and what's the payback? The ECM circs like the Alpha were only $100 (state rebates).

bmwpowere36m3

I check the house this morning, got IDT got up to 68*. There's only a single thermostat in the house right now (kitchen/living room). Overall the house feels warm, I think the bedrooms are slightly higher temp.

After work I checked again, here's a little run log of the boiler/on:


The single thermostat is a round-dial honeywell (set to oil/gas "3-5" CPH). The temp doesn't seem to drop before it calls for heat again… at least according to it and a digital thermometer I have next to it.

What's also interesting it the boiler stay at 100% fire rate and the thermostat is satisfied before hitting target supply temp or limit. I only saw the boiler modulate when it was heating the house initially from 50* and the DWH (took a couple hours of running at 100% before modulating down).

I think I'm going to balance the rooms next, target delta T (prior to adding TRVs)?

And then set and play with the ODR.

bmwpowere36m3

Hatterasguy said:

bmwpowere36m3 said:

Paul48 said:

The variable voltage circulators are expensive, but, then again, what isn't?

True… and what's the payback? The ECM circs like the Alpha were only $100 (state rebates).

You know you could just put a valve on the primary side and slow the flow a bit and increase the ΔT to the boiler? Do it gradually and try to get the boiler ΔT a bit closer to the system ΔT.

I can guarantee that the payback period for that one valve will be about 30 days,

You game?

Good thing my circs have iso valves … tried it tonight. Began slowly closing off the output of the boiler circ. I got the boiler delta to rise from 15* to 30* in multiple heat calls. To early to tell since the last point I have with the 30* delta was a very short call and had a VERY long off period preceding it (compared to the rest of the calls).

Paul48

That was still at 100% firing rate, correct?

bmwpowere36m3

Here's a run from tonight (pretty warm):

<img src="https://us.v-cdn.net/5021738/uploads/FileUpload/a8/d217e8874da583a789d124706b1006.png" />

bmwpowere36m3

Its condensing pretty well, since yesterday it did about 2.5 gals. It has been pretty warm the last two days.

Gordy

You need a little guy with an oar for a pump on the boiler.

Brewbeer

bmw, how are you getting the data out of the boiler?

bmwpowere36m3

The data is right off the display, turn the scroll knob and there's an ARRAY of information. However the system return is not measured by the boiler and thus I have a thermometer installed on the zone manifold return.

Brewbeer

Are you manually entering the data into a table or are you linking the boiler to a computer somehow?

bmwpowere36m3

I should say that the last set of data, is with ODR and boiler pump still throttled (what read 30* delta before).

bmwpowere36m3

G'ole pen and paper… then into excel

Lochinvar has a new BT/WIFI control board (ConXUs, something like that) which lets you view/adjust parameters remotely. I wonder if can data log… not that I have it, but depending on price I'd be interested for long trips/business when I'm away from home.

There is a USB port on the boiler itself, which I think you can connect to… but I haven't really explored it.

Heat_n_CT

I asked about the ConXUs, a retrofit was about as much as a 0-10v v/s pump. Not sure how DIY it is.

Brewbeer

The ConXus retrofit seems to be about as complicated as plugging a video card into a PC motherboard (there is a Lochinvar video of it being plugged in on youtube). I asked about the ConXus board when my knight was installed, but the cost for just the board was higher than I was willing to spend.

I see the USB port on the front of the boiler but I don't have a laptop to connect it up. I wonder if it is possible to plug a tablet into it?

Gordy

http://www.lochinvar.com/_linefiles/SM-PCPII-Rev C.pdf

Heat_n_CT

Now get your hands on the disc.

Gordy

Yup.....

bmwpowere36m3

Another run from tonight at 37* ODT. Heat call was just ending when I got there: 5 min OFF, 45 heat call, 5 min OFF, another heat call.



I did decrease the flow on two radiators and throttled the boiler pump a little more (as it was running ~10* delta). What's an acceptable temp delta between rooms when setting ODR (prior to adding TRVs)? Right now the kitchen/living room are 68* and the two bedrooms are 70-71*.

bmwpowere36m3

All the radiators are off a common manifold, so common SWT. Their returns mix in the manifold return.

I'll throttle the boiler a bit more tmrw. When the heat cycle first starts the boiler delta climbs to 25* and then drops down to a steady state.

As far as room delta, I just meant what should I target before adding TRVs to them (to fine tune the temps). Might as well "balance" the system/temps (68* is comfortable), dial ODR, bump it a few degrees, and fine tune temps in rooms with TRVs.

bmwpowere36m3

Well I set to 30* delta under steady fire... only to find later in the day the boiler would shut down due to "high delta". Essentially it would fire, than ramp to 60-80% and shut down. I tried it at 25*.... same thing.

Once its running steady, 30* is fine... just when it initially fires. So I got it back to 20* which runs fine. I'll have to set a "ramp" to limit the fire, then it should run 25-30* without issues.

bmwpowere36m3

Yesterday, the temps barely fell below 50*. The boiler was cycling quite a bit… it was meeting setpoint (~100*), not thermostat, but the house remained 68*. Cycles 2-3 minutes long, off for 2 minutes.

Anyway, I setup up a ramp: 3 min @ 20% (min fire) and 2 min @ 30%. Run times increased to 10-12 min. Would be longer if I limited the boiler fire rate to 20% and that's it…. however I would have to disable or change it again once ODTs fell again.

The off times didn't change, so I set the anti-cycle (default 1 min) to 5 min, which helped as well. I also throttled the boiler pump to 30* and by setting the ramp it doesn't shut-down on high delta.

Today it has been 30-40*, boiler is purring away with long cycles.

Not that it really matters at this point (doing some remodeling), but the thermostat (cheap round honeywell) acts weird. Temp is set to 68*, it always indicates 64* (however several other digital thermometers say the temps at the same location are 68-70* throughout the day, they display max/min temps for the last 24hrs).

Gordy

A btu made for a btu needed. If my 210000k boiler runs for 10 min an hour it makes 35000 btus gross. If your 55k boiler runs 39 min and makes 35000 btus gross approx. mine is 80% yours is 95% they both just used the same amount of gas gross.

bmwpowere36m3

Not sure what your getting at @Gordy …

My heatloss on design day, IIRC, is about 38k (before planned future addition). Since the boiler can only modulate down to 20%, so ~10k… I assume my heatloss is less than at 50* ODT since it cycling off the set-point and maintaining indoor temps.

bmwpowere36m3

45 min heat call on a 37* night @24% fire… so lets call it 13k BTU in an hour, right?

Gordy

It was not a direct comparison to your load situation. Just an arbitrary number to show how two vastly different style, and sized boilers can satisfy loads.

Paul48

You need to find out why it was shutting down. Meeting setpoint doesn't shut the boiler down. If it was at minimum firing rate and setpoint, then it would shut down, but that indicates a need to adjust the curve.

bmwpowere36m3

Shutting down in the sense of a short fire cycle. It couldn't keep the supply temp below setpoint + 10* (20* differential), so it shut down. As temps have fallen, the supply temps run closer to setpoint or a few degrees higher.

Why? Probably because my house is less than 10k btu/hr loss when its 50* out.