Mod Con boiler supply temps when run with baseboard or radiators

Rich_49

Slant fin sucks . Take a look at this . Use a boiler in the 40 -50 range . Use a manifold with homeruns to each emitter and use the proper piping arrangement for each based on the BTU requirement of each room .
http://www.smithsenvironmental.com/ES_HeatEdge4cBro_SM_4.pdf

bmwpowere36m3

Hatterasguy said:

bmwpowere36m3 said:

Like I said, I was using the default double glazing setting in S/F without thinking about the number (0.65). If I enter 0.28 it's a 5000 BTU/hr difference. I guess it seems small, but all these values add up.

According to the tools:

Walls: ~7000 BTU/hr
Ceilings: ~3000 BTU/hr
Floors: 15000 BTU/hr (first floor, hardwood, over unheated basement).

I always thought the ceilings (0.022, ~ R46) would be the biggest loss, I have R19 and R30 (crisscross) installed. I'm surprised by the floors… 0.15 (~ R7). For the walls the value is 0.07 (~ R14), that agrees with a breakdown I found that included the R value for studs (2x4) at 15% wall coverage and R15 insulation at 85% wall coverage and sheathing/air barrier film/drywall at 100% wall coverage.

I thought the discussion was whether to enter .28 or .33? Yes, .65 is going to have a much larger effect. That value would never be used for any double glazed window.

You've got a serious error in the wall calculation. To lose only 7000 BTU/hr with a 0 degree design day, you'd have 1428 square feet of exposed wall. That's roughly a 13' x 13' x 8' box. Your floor value shows the house is about 30' x 25' (presuming R1).

You can save a massive amount of heat via the floor with the use of a heavy rug. Also, the value for the hardwood can be raised above R1 if there is the typical 3/4" subfloor beneath it.

I don't much care for Slant-Fin as the R values are usually far too conservative and the result is usually inflated.

Yes, but 0.33 is the "value" in the calculator for triple glazed windows/doors. Unknowingly I was using the double glaze value as it made "sense". However that double glaze value is 0.65… Now I'm manually entering 0.3.

The S/F calculator has drop downs with values associated with text, such as: "attic space above, 10 in of insulation, 1/2" drywall = 0.03, or wood over enclosed unheated space no insulation, finish flooring, pine stub-floor 0.15, etc…"

Making it user friendly, otherwise you'd have to manually enter all the U-factors… which now I'm doing for certain things.

House is 1600 sq ft, modeling it as a 40x40' box (for floor, ceiling and infiltration calcs) with 183 linear feet of exterior walls, 8' high (183 x 8 = 1464 sq ft). Full disclosure, I'm leaving out 42 linear feet of wall adjoining an unheated garage that'll i'll use the cold partition wall in S/F and not exterior wall. I'm pretending the inside is empty, only exterior walls/windows/doors. I think that should give me a rough number for boiler size. Then I can do a room to room calc.

Design day 7 F

Floor is 3/4" hardwood over 1/2 plywood on 2x8 joists.

If you know of a better calculator I'm all ears… the three I listed seem to all agree so far within 10%.

bmwpowere36m3

What would be a good infiltration (air exchange/hr) to use?

Gordy

what temp is the unconditioned basement?

I'm seeing an opportunity for the CDN 40. All though it does not have the fire tube HX, and may require P/S if your minimum system flow rates do not meet the boilers min. Flow rate. But then you have that with the whn 55. I would consider a little basement conditioning it will drop the floor load on the main level, and mellow the coolness of a non insulated floor over an unconditioned space.

bmwpowere36m3

Good stuff!

Gordy said:

what temp is the unconditioned basement?

I'm seeing an opportunity for the CDN 40. All though it does not have the fire tube HX, and may require P/S if your minimum system flow rates do not meet the boilers min. Flow rate. But then you have that with the whn 55. I would consider a little basement conditioning it will drop the floor load on the main level, and mellow the coolness of a non insulated floor over an unconditioned space.

I'll take a look. Right now there are no doors in the house (interior, including to basement) and I'm heating with a 80 MBH kerosine heater since where at the stage of taping/compounding.

bmwpowere36m3

58 F upstairs, 52 F in the basement and 20 F outside.

The inside of the house is totally open to airflow, no doors throughout, including stairwell down to basement and no flooring (only ply right now with gaps). Running a 75 MBH kerosene heater (torpedo) on the first floor, set to 65 F or so on its thermostat. It gets very warm upstairs if the heater is turned up, 75 F.

Gordy

Watch the co with that kerosene heater.

bmwpowere36m3

Gordy said:

Watch the co with that kerosene heater.

Thanks, helps that I'm not living there at the moment. What you think about the temps?

So all plugged in to S/F:

1.0 ACH: 42.7 MBH
0.75 ACH: 39.1 MBH

Gordy

Does that include the planned edition? Temps are not bad

bmwpowere36m3

Gordy said:

Does that include the planned edition? Temps are not bad

Yes, 1300 sqft main house and 300 sq ft "addition", which currently is a 3-season enclosed porch.

Rich_49

Have a blower door test done , many local utilities offer this service , sometimes for free . This will give you a dead nuts ACH number . R value has much less impact than ACH .

Gordy

ACH is one of the most over estimated variables. On the other hand it's the hardest to make a constant. Wind speed, and direction effect it along with exhaust fan, and fireplace usage. When talking FA it has effects.

Rich_49

The only house where you know you will be under x ACH is when you build to PH standards . That's why they are tested several times throughout construction . Designing an 11,000+ right now in Akron that is expected to have a .1 ACH NAT . Ready for this , 110,293 BTUh@ 5* , 22mph wind . Take away the fudge and it should really need 88,234 . This house is a pig too , ACH is the key gents . Air sealing is the most important detail in any house

Gordy

Hatterasguy said:

Gordy said:

ACH is one of the most over estimated variables.

How do you know unless you do the estimate and subsequently get a blower door test?

If you have some blower door tests of various houses I'd be profoundly interested in seeing those results.

I find ACH to be a completely blind estimation.

That's why I said estimated when done so it happens that way.

bmwpowere36m3

I've seen values as high as 5-7 ACH, that would be like 100 MBH just for infiltration

Is 1 ACH too optimistic? Also the ACH50 #'s are confusing… We are interested in natural air exchange right? So its Q = 0.018 * V * K * deltaT, where V is the cubic feet, K is the number of air changes per hour and deltaT is the inside - outside temp

Rich_49

5-7 sounds more like an ACH50 number . This is the number most building science geeks throw around and sometime do not convert for us less intelligent . LMAO .

bmwpowere36m3

Hatterasguy said:

bmwpowere36m3 said:

I've seen values as high as 5-7 ACH, that would be like 100 MBH just for infiltration

5-7 ACH is impossible.

A house that has settled badly with leaks all over the sill plates and through the sheathing and windows would probably come in at 2. I cannot fathom anything worse.

Also, as Rich mentioned, if the house is above 1, you can certainly make some changes to reduce it. At those levels, it's low hanging fruit. The leaks are obvious.

So a ACH of 1 would be very conservative? Only factoring the cubic feet of the first floor (not including the basement).

Canucker

5-7 ACH? I have areas of the plant I work in that have 8 ACH as per the testing. It's a little breezy at that rate. I'd hate live in a house with 5-7

bmwpowere36m3

Lets talk about zoning for a minute… before I was thinking of doing multiple zones/thermostats. However I understand that leads to inefficiencies given the heat load on each zone.

My habits are to maintain an indoor temp of 68-72 F during the day in all rooms and have a lower temp of 62-65 F for sleeping (at least the bedrooms). I wouldn't mind having the M.Bath at a higher temp overall.

Given the layout:

Would it be good (for now, not including addition) to have 2 zones.

Zone #1: Kitchen and Living room (both fairly open to each other with a 12' opening). 15,800 BTUs/hr, thermostat in kitchen.

Zone #2: M.Bedroom, M.Bath and bedroom. 16,300 BTUs/hr, thermostat in M.bedroom.

SWEI

Hatterasguy said:

recovery from setback is impossible with a properly programmed modcon. You'd have to adjust the curve at least 10°F higher to get any decent recovery time.

Most mod/con controls have a "boost" feature you can use to overcome this.

@SWEI has setup mod-cons that don't use a thermostat. Now there is some brilliance and some work to get it running perfectly.

Thanks, but I can hardly take credit for this. The Europeans have been doing it for a long time.

SWEI

Here's a description of the feature from Triangle Tube:

Boost Feature Setting
(Parameter 19)

The Boost Feature is available when a room thermostat is selected for the CH operating signal with Parameter 45 and an outdoor temperature sensor is connected to the boiler. This feature can be used to compensate for a low outdoor reset schedule or to provide a quicker morning recovery.

If a call for heat is not satisfied in the time period set by this parameter, the CH setpoint will be raised by 18°F.
The CH setpoint will continue to be raised by 18°F for each time period that the call for heat is not satisfied until the CH Maximum Boiler Operating Setpoint (Parameter 4) is reached.

Once the call for heat has ended, the CH setpoint will decrease by 2°F per minute until the original CH setpoint is reached. If a call for heat occurs while the CH setpoint is decreasing, the boiler will operate at the current CH setpoint. The Boost Feature will still be active and will raise the CH setpoint by 18°F if the call for heat in not satisfied in the time period set by this parameter.

bmwpowere36m3

Hatterasguy said:

You do realize that the concepts of zoning and setback are ideas of the past?

With a mod-con that operates on outdoor reset, the goal is to start it up in the fall and have it run continuously until the spring. This can be done if the boiler is close to an exact match for the heatloss on the design day.

Once you start screwing around with zones, all bets are off and the mod-con will start cycling (for sure under lightly loaded conditions).

If you must have the bedroom cooler at night, just allow the entire house to drop in temperature. But, realize that recovery from setback is impossible with a properly programmed modcon. You'd have to adjust the curve at least 10°F higher to get any decent recovery time. It's like accelerating a car. It goes at 60 mph effortlessly on 15 hp, but if you want to accelerate it from 30 to 60 mph in a reasonable time (say 15 seconds), you need 100 hp. Boilers are a similar concept, but the "horsepower" comes from higher SWT's.

@SWEI has setup mod-cons that don't use a thermostat. Now there is some brilliance and some work to get it running perfectly.

I understand, at the same time I've heard that rarely any designed/installed heating system in a residence operates at 100% even at the design day. Leading to the conclusion that most systems are oversized to the actual heat loss.

However is some "reserve" a good thing…. There is always the possibility of sub-average temps or change in heat loss of the building with time (wood shrinks, cracks form, windows seals degrade, insulation loses R value as it settles, etc…).

Is having a boiler running 100% of the time negated by running circulators 24 hrs/day? With a boiler running 100% of the time, just to provide heat, would have to upsize anyway if you wanted hot water on a design day… right?

Based on posts here, I was under the assumption that most of the heat loss tools are padded anyway. So if you size a boiler at least to the size of design day heat loss (or next closest one), you have a "reserve" in heating capability? Is in on sub-design day temps or additional heat loss or heating from set back (reasonably outside temps).

Maybe I need a professional, as there are a LOT of variables, needs/desires/expectations and ultimately system performance.

bmwpowere36m3

My plumbing supply guy is an aquantence of my father's. I told him I needed a whole new heating system in the house because I was renovating and the pervious system was likely 25 yrs old. He did some calcs and told me the Lochinvar WHN085 along with a Crown Megastore tank would work, emphasizing the Lochinvar unit is very efficient.

I know he doesn't install or design systems, nor claims to be.

I came here, because like anything else I do my own research and ran some calcs. It been stated that a 40-50 MBH unit should suffice… so I guess that's how we got here

bmwpowere36m3

What I'm looking for is probably the same as everyone else. A comfortable home that's efficient, i.e savings on fuel.

However I don't need to squeeze that last 5% (arbitrary number) of efficiency out of this system at the expense of a very complicated system (which I know I can't do myself), comfort or upfront expense. Do I need a mon con boiler… I don't know, that's what was proposed to me.

SWEI

The "reserve" you speak of is already factored in when you use a heat loss calculation program. If there are sustained periods of colder or windier conditions than the "official" design day, use those numbers when you run the calcs. A properly sized and installed mod/con boiler (this means no micro zoning) will run continuously during colder periods and nearly flat out on a design day. Because it's running all the time, it doesn't need the "pickup factor" that a conventional boiler does. ECM circulators draw very little power when properly sized and piped - typically between 5 and 40 Watts. If you want simple and reliable, start with the idea of a single zone for the whole house. If you have rooms with solar gain, a woodstove, or are infrequently occupied, those might be worthy of another zone or two. Not eleven.

bmwpowere36m3

SWEI said:

The "reserve" you speak of is already factored in when you use a heat loss calculation program. If there are sustained periods of colder or windier conditions than the "official" design day, use those numbers when you run the calcs. A properly sized and installed mod/con boiler (this means no micro zoning) will run continuously during colder periods and nearly flat out on a design day. Because it's running all the time, it doesn't need the "pickup factor" that a conventional boiler does. ECM circulators draw very little power when properly sized and piped - typically between 5 and 40 Watts. If you want simple and reliable, start with the idea of a single zone for the whole house. If you have rooms with solar gain, a woodstove, or are infrequently occupied, those might be worthy of another zone or two. Not eleven.

Eleven? I have laid out two on the drawing (red, being one and yellow the other).

First zone, has the living spaces (kitchen + living room) at 15,800 BTUs/hr and the second zone, the sleeping areas (M.Bedroom, M.Bath and bedroom) at 16,300 BTUs/hr.

One zone for the whole floor would be 32,100 BTU's/hr. That would require a somewhere between 64 delta t @ 1 GPM to 32 delta t @ 2 GPM. I assume the output of the emitters is pretty much the same between 1-2 GPM, right?

My concern with only having 1 thermostat is if I calculated anything wrong I'll end up with cooler/warmer rooms. I really like to have a cooler bedroom when sleeping… just used to it.

bmwpowere36m3

SWEI said:

The "reserve" you speak of is already factored in when you use a heat loss calculation program. If there are sustained periods of colder or windier conditions than the "official" design day, use those numbers when you run the calcs. A properly sized and installed mod/con boiler (this means no micro zoning) will run continuously during colder periods and nearly flat out on a design day. Because it's running all the time, it doesn't need the "pickup factor" that a conventional boiler does. ECM circulators draw very little power when properly sized and piped - typically between 5 and 40 Watts. If you want simple and reliable, start with the idea of a single zone for the whole house. If you have rooms with solar gain, a woodstove, or are infrequently occupied, those might be worthy of another zone or two. Not eleven.

So would that reserve be capable of heating the house in the morning from a setback of say 5-10 degrees in a resonable amount of time? I know, I know… depends on outside temp, heat loss and boiler size.

What is considered a micro zone? Less than the min firing rate of the boiler? For example a WHN085 is 85/17 MBH max/min and its IBR is 69 MBH. Can it be inferred that the min IBR is 13.8 MBH?

Gordy

Set backs, and outdoor reset are counter productive. Your new WHN will have ODR on board. It would be hard pressed to lose 10* in a twelve hour period or even longer with the insulation, and envelope upgrades you have done. Yes if you are designing your boiler size on the edge then it would take long periods to catch up coming out of setback.

I believe in setbacks for extended periods away say on vacation, or a weekend away. Daily I find the savings negligible for the loss in comfort due to MRT lagging coming out of setback.

Gordy

Hatterasguy said:

You mentioned that ACH is one of the most overestimated variables.

I'm interested to know if you have any supporting data for this? I tend to agree that we probably overestimate ACH, but without any confirmation, it's all heresay.

What do you use for ACH in a typical house built in the '60's?

The only supporting, or here say evidence is the built in fudge factor of say the slant fin program. You know as well as I do that what the program tells you the heat loss numbers are in real life it is quite a bit less10-20% not their fault they don't know who's using the free program, and the aptitude of the individual inputing the numbers.,even when inputs are accurate. It is what it is free. As displayed in this thread.

What would I use for a 60's built house. That is a silly question. To answer that with a number would be like saying all 60's automobiles get 15mpg. There are quality built houses from the 50's with no envelope upgrades that could out perform some of the 21century garbage out there. The right answer would be What a blower door test result would conclude. To many variables. Even with a blower door test one has to look at ventilation habits right down to loads of laundry a day with a dryer going all day sucking air out of a house. Exhaust fans, fireplaces usage, house location.

Rich_49

Rich said:

Slant fin sucks . Take a look at this . Use a boiler in the 40 -50 range . Use a manifold with homeruns to each emitter and use the proper piping arrangement for each based on the BTU requirement of each room .
http://www.smithsenvironmental.com/ES_HeatEdge4cBro_SM_4.pdf

Maybe you should read this post again . In this way , later you can zone however you want by adding actuators . Actually open the link and look at the baseboard . Hint ,both bedrooms on one zone may not work as you think , they have different characteristics and exposures Goldilocks . Do radiant in the bath because you can't put enough baseboard in that monster to make it comfortable , wet naked people need building science too .
How did you enter the R values for walls and such , did you layer all the wall sections ? A wall is not just insulation it is an assembly .
Buy a phoenix water heater , FPHX , 2 pumps (ecm) and an outdoor reset mixing valve and be done . It will never short cycle and you'll have no standby loss because you'll be heating the house with it . Looking qat the bb lengths you are thinking of you can use 130* water with the Smiths .

bmwpowere36m3

Gordy said:

Set backs, and outdoor reset are counter productive. Your new WHN will have ODR on board. It would be hard pressed to lose 10* in a twelve hour period or even longer with the insulation, and envelope upgrades you have done. Yes if you are designing your boiler size on the edge then it would take long periods to catch up coming out of setback.

I believe in setbacks for extended periods away say on vacation, or a weekend away. Daily I find the savings negligible for the loss in comfort due to MRT lagging coming out of setback.

For me lower night temps is all about sleeping comfort… that's what I grew up with (maybe parent's were trying to save money ) and I sleep better.

About losing the 10* at night… do you mean a house heated to say 70*, boiler turned OFF (no heat input), would take over 12 hours to drop to 60*?

I have a thermometer inside the house now and all I know is when the torpedo kicks off its maybe a few minutes (call it 5-10) before the room temp drops a degree or so. Granted it's probably due to the heat distributing throughout the house as the torpedo is in a central location.

bmwpowere36m3

Gordy said:

Hatterasguy said:

You mentioned that ACH is one of the most overestimated variables.

I'm interested to know if you have any supporting data for this? I tend to agree that we probably overestimate ACH, but without any confirmation, it's all heresay.

What do you use for ACH in a typical house built in the '60's?

The only supporting, or here say evidence is the built in fudge factor of say the slant fin program. You know as well as I do that what the program tells you the heat loss numbers are in real life it is quite a bit less10-20% not their fault they don't know who's using the free program, and the aptitude of the individual inputing the numbers.,even when inputs are accurate. It is what it is free. As displayed in this thread.

What would I use for a 60's built house. That is a silly question. To answer that with a number would be like saying all 60's automobiles get 15mpg. There are quality built houses from the 50's with no envelope upgrades that could out perform some of the 21century garbage out there. The right answer would be What a blower door test result would conclude. To many variables. Even with a blower door test one has to look at ventilation habits right down to loads of laundry a day with a dryer going all day sucking air out of a house. Exhaust fans, fireplaces usage, house location.

That's my concern… all these variables. In a perfect world, boiler running 24hrs/day = super efficient. You're habits slightly change and the boiler can't keep up. If you nailed the calcs down to a "t", would you consider a safety factor? 10, 20, 30%?

Gordy

Your house is in no way in the same state of MRT that it will be when occupied with furnishings, and at a steady state temperature. Think about all the objects that have mass in an occupied home. The drywall has mass. You may have noticed when delivered, and stacked in rooms the cold mass of the drywall that was sitting outside until brought in your house to warm up that did not happen in minutes.

Gordy

That's my concern… all these variables. In a perfect world, boiler running 24hrs/day = super efficient. You're habits slightly change and the boiler can't keep up. If you nailed the calcs down to a "t", would you consider a safety factor? 10, 20, 30%?

That's why they are called habits, repetitive actions. So long as habits stay the same.

Remember your design days are few. How many days in your location has the design temp you are using sustain for a whole 24 hour period? Usually the coldest part of the day is early am.

Even if you were to dp below design day temps the duration is not usually for a full 24 hours.

Scenerio: say it did happen. Say it was 5* for 24-48 hours then maybe your setpoint would only be able to maintain 62*so ha gotta dress a little warmer, and throw an extra blanket on for a short period.

Play around with even the slant fin calculator. Change your design temp to what ever you may deem worst case, and then drop your room setpoint until you get the same heatloss load as with your existing calcs. That should be where you would end up in a below design day scenario. Again that would have to be 24 hours or more to get that effect.

bmwpowere36m3

Gordy said:

Your house is in no way in the same state of MRT that it will be when occupied with furnishings, and at a steady state temperature. Think about all the objects that have mass in an occupied home. The drywall has mass. You may have noticed when delivered, and stacked in rooms the cold mass of the drywall that was sitting outside until brought in your house to warm up that did not happen in minutes.

True, thought about that after posting… but the drywall is already up and taped

Gordy

Right, and you are not holding occupied setpoint for any meaningful duration. Mass has a flywheel effect. Take room temp down MRT lags. Bring room temperature back up same thing.

bmwpowere36m3

Right on Gordy!

I was thinking about getting a blower test as part of a subsidized energy audit. If its not too much, then its a small investment in planning the system. I think its ~$100.

Gordy

"No, it's not a silly question. You and I both know that there is NFW that you're going to do a blower door test for each prospective customer. Therefore, you must make some assumptions for ACH depending on the construction. You start with a given ACH and make adjustments based upon the variables that you know".


Your right I should have said umbrella, not silly. just saying its case by case, I think you agree. Yeah NW on the blower door, but would be the best answer.

bmwpowere36m3

Gordy what you think about the zones, two okay for the main portion of the house? Right now on design day (1 ACH), I can supply 165* and return at 135* (room/bb in series). With ODR the supply temp can be lowered as the temp rises outdoors. However I might run into an issue with bb output when the return temp from the last radiator drops below 120*?

Gordy

I think you should seriously consider the higher output base boards Rich suggested. jMHO. You can get by with either less base board, or same baseboard lengths with much lower AWT.

Also the radiant in the baths are a nice touch of elegance especially if tiled. It's not to late yet for a sandwich install.