Homeowner with WHN questions

Heat_n_CT

Had a WHN055 installed P/S to 2 zones with about 50' of fin tube per zone last year (actually this year I guess, last season). My house has a heatloss of 33k on design day, so yes the 55 is oversized. What's happening is of course the 15-58 (speed 1) boiler pump is pushing higher GPM than the system is taking so my already heated water is mixing with the return water and making the boiler reach the set point very fast - this is pretty common no. I set the set point differential to 20* so I get some length out of my burns, I think in the not so cold times I get 15-20 mins burns, my ODR is set for 130/105 at 5/65 and I set the anti-cycling to 10mins. The last real cold spell last season I had 18-30 hours burns. It's always (whenever I look) at 20% for the modulation, probably because already heated water is just coming right around again to flow thru the boiler. Only time I see the modulation rise is when the 2nd zone pops and it gets the rush of that cold water, and of course during DHW. I have a digital supply/return sensor attached at the right places and I get a 10*-15* dT. Thought about combining zones, but upstairs (sleeping) is always 63 while down is 66-68.

I did mess with the boost that the Lochinvar has in its ODR settings, but watching it boost I see it getting up to 150-160* water by the end of the cycle. That in itself raises one question: what's more important returning <133* water or no short cycling...if 15min burns is short cycling? Start from 105* it can take 30-45mins to get to the 150* I mentioned.

I'm on the verge of buying a Taco 006-VVF4 0-10v pump. I don't like the price or the fact it's not ECM, but I'm tired of seeing this thing not function the way I hear it should, Taco probably doesn't eat any more electricity than the 15/58. The only thing I'm apprehensive about is connecting the 0-10v wires to the boiler.

So to recap, I guess my questions are do I leave the boost and finish the cycle with >150* water? And is the high price of the 006-VVF worth it on my system. Just throwing this out there...could I use the Alpha as the boiler pump? Man do I wish they installed isolation flanges!

Oh, one other thing. When the boiler comes on its modulation is set for 65%, it's only there for a few, but is there any way to get that to start at 30-40% instead? Or is it 65% to assure a strong flame? I can't find anywhere in the menus or manual for that function.

Thanks.

Zman

As much as I agree that it would be nice to have a wider boiler delta t, It has nothing to do with your problem.
At 180 degree water temp your radiators would absorb somewhere around 25 k/btu. With 130 degree water it would be less that 1/2 that. At your typical day heating day you will be putting out even less than that. If your system is zoned the problem gets even worse.
Your boiler is producing way more energy that the emmiters can absorb.That is the problem.
A wider delta t at the boiler will not change the boiler cycles at all.
I don't see a solution to your problem that does not involve a buffer tank.
Post a little more info about the zones and we can get you headed in the right direction.

Heat_n_CT

In 40-45* temps my single zone load is barely 8k btu, about 6k for the second floor. I've thought about changing out the existing fin tube for higher output ones, hoped changing a pump would've been the silver bullet.

It was hard enough to find someone to install the boiler properly...buffer tank should be fun to try and find.

Zman

A far as I can tell, with the setpoints as is, with one zone (25') of base board calling with an average water temp around 110 degrees that zone is putting out about 3750 BT/hr. By using the boost setting the boiler eventually increasing the water temp to 150 degrees the zone is giving an output of 8750 btu/hr.

My first observation is that the outdoor curve is not set correctly and the only reason the house is heating is that the boost feature is making up for it.

If the heat loss provided is correct, the boiler should be at 200 degrees on the design day. Given that heat loss numbers are usually inflated, I would think a heat loss curve of 160-170 on the design day and 120-130 on the warm day would be more accurate.I don't understand why you would use boost feature in a multi zoned system. The boiler does not know if a call is one long call or 2 shorter calls, making the feature less than effective.

Changing these settings combined with the short cycle features, may solve the issues without a buffer tank.

As a separate discussion, having nothing to do with boiler cycles and loads, the system would be more efficient if the delta t on the boiler loop is increased.

Brewbeer

I just install a WHN055 in my house, which has a similar heat loss as yours. See the "FHA to HWB conversion project" thread for details on my system. Because of short cycling concerns I opted for a buffer tank. Having the buffer tank really helps keep the system temps way down in the condensing range. Boiler has yet to fire over 20% or over 125F SWT in space heating mode, even when we had those nights in the low 20s earlier this week.

Heat_n_CT

I've only used the boost for the last two days so let's not put too much into that equation.

Re-ran heatloss and I get 35k, 20k main floor and 15k second floor. Each zone carries 50', the whole house is 100'.

Correct me if I'm wrong, but I hear you saying my ODR should be more like 160/125, I had hoped for lower temps.

bmwpowere36m3

I have the same boiler installed in my 1300 sqft ranch. Design day for me is 7* and I currently have three panel radiators installed in the house (all one 1 zone).

I originally ditched using the 15-58 (or whatever Loch provides) due to high boiler GPM (calculated). Note my primary/secondary piping is all 1". I opted for the Grundfos Alpha on both the boiler and system loops. Even with the Alpha turned down to its lowest speed, I still get ~4-6GPM (per the readout) and initially I saw a boiler delta of 15* (with setpoint at 180*, no ODR). I turned the isovalve on the output of the pump to see a boiler delta of ~30*.

However now that I have the ODR running… with the boiler pump still "throttled", I'm seeing 5-10* boiler delta. My setpoint is now between 90-105 degrees based on ODT of 50-60* (today and yesterday).

But since the setpoint is low, the boiler is still condensing like crazy at these higher outdoor temps, with no short-cycling.

We'll see when it gets colder, but even the Alpha pump I think is overkill. Because I could run it at its lowest speed, lets call it 4 GPM. So with a max output of 50k BTU I can only expect a boiler detla of ~25* (maybe more, since my system delta is ~40*).

Anyway, the ECM crics like the alpha were $100 with state rebate and they consume little power. Not sure how much of a smaller pump you can get or a variable-speed, boiler controlled… but those are big money (I already asked, probably not worth the investment).

Try what Hattersguy (spelling) mentioned, either put in an iso flange on the output of the boiler pump or a butteyfly valve in the loop. It worked for me to raise the boiler delta. Depending on what an Alpha costs you, maybe worth getting that or Tacos bumblebee or viridian…. I think there all in the $200 range (pre any rebates). Look at the pump curves (for constant-speed, no delta t or p) and figure out your boiler loop headloss is.

I used the Loch supplied 15-58 to run my DWH loop (it works fine, 3/4" piping, 6-8' total, Crown megastore 50 gal tank).

Zman

No,
Those numbers were based on 50' total. If you go to the manufactures website or slant fin if you are not sure, you can look up the output of your heaters at different water temps. From there you can determine the correct temps.
My point in all this is that the circ speed only effects a few percent of efficiency in the boiler and the circs electrical usage. It is unrelated to the cycling or modulating conversation.

In reality your boiler will run most efficiently with, low return water temps, at lowest modulation, running long cycles and properly tuned.

bmwpowere36m3

I can't recall the model of Viridian (spelling), but I think it was Tacos answer to delta p…. I believe it could do: constant speed, delta t and delta p. From what I remember, it could go lower (GPM at similar head loss) than both the Alpha and Bumblebee.

Oh, and my design day heat loss is ~ 29k BTU (calculated), but I plan to up the sq ft of the house in the near future. Now that the boiler is running on ODR, its throttling down to 22-28% FIRE with 50-60 ODT. When I had the fixed set point of 180* initially, it would only fire 100% and run for 5-10 min (per heat call), depending on ODT (I assume).

Heat_n_CT

Phew, glad I don't need 200*. Based on the suntemp spec sheet I should be able to heat on design day with 145-150* water. Guess 130* was set a bit too low?

BMW, I followed your setup last year. Maybe I'll swap the alpha on the indirect with the 15-58 on the boiler.

Brew, I'll look it up thanks.

ced48

Why not go to one zone, that would solve your problem? Also, a Taco 1816, set quite slow, would make a good boiler pump, as well as a system pump.

Heat_n_CT

We couldn't sleep with a bedroom at 67 or 68. I know I could set back, but thought that was not a good thing with hot water systems.

Do I have to worry about low flow thru the boiler with the alpha or 1816? I may not have my head wrapped around this, but how would the pump do if the modulation started rising to 30 or 40% or 50%?

ced48

Unless you hit the perfect ODR settings, you are always going to be producing slightly more heat than you need, so setting the whole house back 2 degrees or so at night, will be just fine.

You will have to keep the flow adequate for the highest firing rate, but on your boiler, even the low speed on the Grundfos is more pump than you need.

bmwpowere36m3

The loch boiler will lockout if the boiler loop delta gets near 50* (IIRC). So say you want to have a 30* boiler delta at max fire (which you can limit, the fan speed that is or set up a slow ramp up).

Following hydronic formula: 51k BTU, 30* delta = ~3 GPM. You can go lower, so long as the boiler doesn't go 100% or run a delta closer to the "lockout" of 50* or so degrees.

If you limit the boiler fire rate, maybe you could go down to 1-2 GPM. But if you set the ODR to aggressive, the boiler won't have the "umphf" to recover from setbacks or some extreme temp spells.

Since the pump is fixed speed, whatever the delta is at 100% fire, it'll only decrease with fire rate and SWT. That's where a variable speed boiler (controlled) pump is nice, since it'll vary speed with fire rate. So it should keep the boiler delta more consistent.

In the end, all that really matters is the return to boiler water temp. Even if the boiler delta is only 5-10 degrees... keep the return temps below 130* and you'll be condensing.

hvacplumber7

Have you looked into the ramp delay setting. It allowed you to setup to 6 different firing rates and times. So you could bring the boiler on at 20% right from cold start and will increase your run times. Otherwise the boiler will come on, and modulate right up to 100% to get to temp set point ASAP.

Heat_n_CT

I guess I was playing the uneducated game "lower the better" and fooling myself that I was doing something good. I guess if I need 145-150* at design day of 5* I should have that as my high temp in the ODR. I was hoping 130* on the high end would've forced me into more condensing.

In the meantime I guess if there is no harm in putting the Alpha on the boiler and the 15/58 on the DHW I'll give that a whirl this weekend.

HVPlumb7: I thought about the ramp, but I see this thing so infrequently at anything above 20%-30% I'd be afraid it would shoot way over the set point after the first step.

hvacplumber7

I believe you can program the ramp to stay at 20% for hours if you want. Plus even if you do want it to ramp to 60-70% the boiler will still over-ride the ramp and modulate down if you start approaching your setpoint. It will just keep the boiler from going into high fire and will slow how fast you get to your boiler setpoint.
I have a house that is running a retrofit in floor system with aluminum plates. 3 zones and a heatloss of about 30,000 btu's. Same whn-055 boiler with max water temp of 140*f at -15. My average boiler run time is 45 min. Just my 2 cents

Harvey Ramer

@hvacplumber7 is giving you some good information. Setting up those ramp delays goes a long way to eliminate short cycling.

Paul48

Shut the boost off...it's counter-productive, as it raises the supply temps.

Heat_n_CT

Boost is off, it was just a two day test.

I'll try the ramp delays.

Heat_n_CT

Ok, stupid question coming...limit is exactly that, just a limit - even sounds stupid typing it. It's not saying that after 20mins it'll kick up to 30%, it will just limit it to a modulation to between 20%-30% if anything over 20% is needed to match the set point?

Paul48

Get the flow down through the boiler. Combine the zones......Put something over part of the fin-tube in sleeping areas...basically making the emitter smaller. Build up of pet hair in fin-tube can render it useless. So, I would think covering part of the fins with foil tape should work.

Carl....He said 50ft per zone

Heat_n_CT

Alpha is now the boiler pump and the 15-58 is the DHW pump. Alpha on speed 1 displays 5 sometimes 6 GPM. Anyone care to guess what the 15-58 in speed 1 was pushing as the boiler pump?

Messing around with the Alpha in anything but const speed 1 I get flows of 10-11-12 GPM.

Supply Alpha has always been on Auto Adapt, which yields 1GPM with one zone and 3-4GPM when both zones are open.

When both zones were open and and the pump outputs were just about equal the WHN return was the same as the digit-stat return that's placed before the return of the closely spaced t's. delta T was around 10...then zone two closed and delta went to 3-5 like before I did the swap.

Going to look into an iso flange put after the boiler pump and also combining zones. Flange I might be able to do, combining probably not a DIY I'm up for.

I do have a valve that's on the outlet leg that's just before the closely spaced tee. Can I throttle that down to slow the flow before it turns the corner or mixes with the return water?

Best pic I have before I did what I could with pipe insulation.

Paul48

The zone valve for the second floor should have a manual by-pass lever on it. Put it in by-pass and turn the second floor t-stat off. The handles appear to have been removed from the valves in the primary loop. They are there in one picture and not the other.

Heat_n_CT

Ok, I see. So with the 2nd floor forced open but t-stat off it will always be open, which works well since the 1st zone will turn on/off the pump?

I don't get what you see or not see. Nothing has been remove from one pic to the next.

Here is my wiring setup...

Paul48

The zone valve should work like that. No need to play with the wiring. It was just the angle of the camera, that made the handles look like they had been removed. Moving either of those handles will bring you DT in the boiler up. If you do that, make tiny moves of the handle, and watch for changes in the DT. Have patience. Did you see the by-pass lever on the zone valve?

Heat_n_CT

Yes, I've messed with the lever before. Thanks!

Here I was thinking I'd have to cut and rejoin pipes.

Heat_n_CT

Can you explain "two delta T's". Are we talking the one on the boiler readout and the one on my strap on digi-stat?

Heat_n_CT

Ah, ok. Digistat yields virtually the same as the infrared gun on a piece of black tape. Thanks.

Heat_n_CT

An update if anyone is interested. Set the Ramp Delay to the full 20min per % interval. I swapped the 15-58 for the Alpha, set zone 2 to permanent open and running everything off the 1st floor t-stat.

Here’s what I see:
I understand the Alpha’s readout isn’t 100% accurate, but the Alpha in Sp1 reads 3-5gpm. System Alpha is set to Sp2 and reads 4gpm. I think the combined Wattage for both pumps are about 29?

Return temps on Digi-Stat readout consistently matches the WHN display for the first time ever. Finally I’m getting return water below 110°. Am I right that 110* probably pushing 92% efficiency? With the whole house online I don’t ram right into the set point in a matter of minutes.

Supply temps vary by a degree or two. I’m guessing boiler outlet water is slightly mixing with some return water at the CST.
Delta T is observed from 7*-12*, that’s never been more than 3*-4*.

2nd floor is pretty warm yet not unbearable – maybe a degree or two warmer than downstairs, makes sense I guess since the heat loss is not as demanding as the 1st floor. At least now the wife can go upstairs to the office and actually use the desk to study…instead of the dining room table.

Ramp works great, for the first 20min it claws little by little at the set point. At the next interval it never goes above 25%-27%.
In 8hrs I had 8 cycles with 5hr run. Tonight I’ll tune the ODR a bit better, I’ll try SWEI’s advice and put the t-stat to 85.

Questions:
Is it safe to assume that if I was underpumping the boiler the outlet display temp would rapidly soar?

Why does the Alpha boiler pump soar into the 8-9-10-11gpm on anything but Sp1?

ODR tuning…what are the best points to start adjusting first? Right now I’m 145*/100* for 5*/65*. IIRC last year I needed 145* on the 0*-5* nights and 150*+ when we had the real sub-zero stuff with wind.

Thanks.

Heat_n_CT

LOL, ok.

ced48

Just so you know, the GPM readings on those pumps are totally useless. It is impossible for a pump to electronically know how much water it is pumping.

hot_rod

ced48 said:

Just so you know, the GPM readings on those pumps are totally useless. It is impossible for a pump to electronically know how much water it is pumping.

Correct, they can be 80% off on those flow read outs. I'm not sure they are a good value, they mislead folks often.

bmwpowere36m3

There's no flow switch on the Lochinvar (its an optional item)... however it'll go into lockout if the flow is too low by the fact the output temps will skyrocket (and/or if the boiler delta goes about 50*, IIRC). That has no bearing on systems temps if piped P/S.

bmwpowere36m3

ced48 said:

Just so you know, the GPM readings on those pumps are totally useless. It is impossible for a pump to electronically know how much water it is pumping.

hot rod said:

ced48 said:

Just so you know, the GPM readings on those pumps are totally useless. It is impossible for a pump to electronically know how much water it is pumping.

Correct, they can be 80% off on those flow read outs. I'm not sure they are a good value, they mislead folks often.

Maybe not accurate, but ballpark… as in if the display is saying 4 GPM, I doubt your actually seeing close to zero flow or 10+ GPM (made-up numbers). The Alpha on my system agrees with the flow-meter indicators on the manifold (unless those aren't accurate as well). The Alpha read 2 GPM and the flow meters totaled 2 GPM as well. The Alpha also only reads out in 1 GPM increments.

I find it hard to believe that based on rotor RPM and amperage draw… you couldn’t create a table for flow rates based on testing.

Heat_n_CT

I had a weekend of HL lockout when the original 15-58 kicked after about a month...didn't run in sp1 after DHW changeover, but sp2 and sp3 worked - tech said just leave it in sp2. it was replaced.

i'd love to get some flow meter indicators, but that's not something i'd tackle myself, never soldered before.

i still can't get over my return temps are actually matching...finally!!

ced48

No-They are not even close to being "ballpark"-Taco has eliminated the "feature" on the new 2218's, because the readings were a joke on the old Bee's.

Sure, they might be right in certain systems, at certain times, but that's just by chance.

Gordy

You would do far better calculating your own head loss, and using pump curve charts. Been done that way for years.

bmwpowere36m3

ced48 said:

No-They are not even close to being "ballpark"-Taco has eliminated the "feature" on the new 2218's, because the readings were a joke on the old Bee's.

Sure, they might be right in certain systems, at certain times, but that's just by chance.

Just for giggles... I noted the boiler fire rate (inferring BTU/h) and delta T. Calculated GPM was similar to displayed, within 10% (I checked the delta and fire rate at a few points). So calculated GPM, matches flow-setters, matches pump display within 10% (at flows 1-5 GPM).

Their not THAT far off... definitely in the ballpark, not out of it. Again, just MY experience on MY system, with Alpha pumps.