Dual Thermostats - 1 system Pump/Zone

TerrS

Wasnt sure of the title for this and searched the forum, but didnt see a match.

So in another thread, I was asking about zoning my boiler, and there are pluses and minuses. Besides costs to install the valves, mostly I think its a concern about short cycling.

But here is issue, My first floor is warm, mostly because I use a fireplace to supplement my heating cost, which is at the expense of my 2nd floor, since the one thermostat is in my dining room and far removed from my upstairs.

So the question is, can you have 2 different thermostats, controlling the same system, pump and controls? If possible, can you give me the readers digest version of how??

In asking that, Yes, I understand without zone valves to control were I will be sending the heated water, that my first floor might become over heated, if the 2nd floor calls for heat, that just means that my fireplace would probably not run as much if this happens.

Is there a better alternative?

HomerJSmith

Yes, But what type of thermostats? The thermo that has the highest setpoint will control.

rconkling

TRVs

TerrS

HomerJSmith said:

Yes, But what type of thermostats? The thermo that has the highest setpoint will control.

Yes I figured that, but what if they are set at the same temperature. I am looking at more insulation for my house currently, but there is around a 5-7 degree temperature difference between 1st and 2nd floors.

They would just be standard digital programmable t-stats.

Jamie Hall

You can either look at it as the higher set point controlling -- or the space with the lower temperature (and probably less radiation in relation to heat loss). The only situation where things get interesting is when the setpoint of the thermostat in the cooler space is set below that in the warmer space. That can give some really weird short cycling problems.

KC_Jones

How do the pipes know where the thermostat is? The answer is they don't. A thermostat is a switch, just like a switch for a light in your house. Move the switch to the garage, the light still works the same. The thermostat will read the temperature of whatever room it's in and run the heat until that room hits the setpoint, but in your case it's running the heat for the whole house until that one room reaches setpoint.

I've seen this suggestion before and it makes no sense. If you currently have a 5-7 degree differential from first to second floor, then you will continue to have a 5-7 degree differential unless you do something with the piping which could be as simple as throttling a valve to one of the areas, if it's so equipped.

If you have valve you want to lower the flow to the warm area and increase the flow to the cold area, especially if you are running that fireplace a fair amount.

MikeAmann

TerrS said:

My first floor is warm, mostly because I use a fireplace to supplement my heating cost,

I hope you are aware that 90% of the heat produced by that fireplace goes up the chimney.
The other thing is......... any form of combustion requires air. And in your case, that will be the same air that your boiler just heated.
Aside from the area directly in front of your fireplace that is nice and warm, your fireplace could be acting like a giant shop vac, sucking up your heat and transferring it outdoors.

TerrS

MikeAmann said:

My first floor is warm, mostly because I use a fireplace to supplement my heating cost,

In most houses that could be very true, but all my chimneys have 3 dedicated flues. So my boiler never sees what's happening in the other flues.

Jamie Hall

TerrS said:

MikeAmann said:

TerrS said:

My first floor is warm, mostly because I use a fireplace to supplement my heating cost,

In most houses that could be very true, but all my chimneys have 3 dedicated flues. So my boiler never sees what's happening in the other flues.



What was meant was this: in most fireplaces (not all, but that's another more complicated story) a good deal of air is entrained by the fire and sucked out of the room and goes up the chimney with the smoke from the fire. That air was heated -- assuming you have the heat on in the house -- by your boiler through the radiators or whatever. The boiler draught isn't affected by the fire, as, as you note, it should be in a separate flue. But the heat it produces does go into the house -- and that heated air does up the chimney with the fireplace.

Now that is not to say you can't use a fireplace to make a warm area in an otherwise cold or cool house, and that can, done conservatively, supplement your other heat -- if you don't mind keeping the rest of the house colder.

Further, some fireplaces -- not many, but some -- have a much better efficiency at heating the space in which they are located. This comes in two ways; first, the chimney is built in such a way as to minimize the excess air while maintaining a good draught. Second, the fireplace itself will be very shallow with angled out sides -- one I know of (built in 1893 -- for instance is 4 feet wide at the back, 8 feet wide at the hearth, and only a foot and a half deep from the front to the back. It does heat spectacularly well -- but as you can see, the fire is almost in the room.

SuperTech

@MikeAmann is correct about the inefficient nature of the fireplaces. And anything that is going up any of the flue pipes is going to affect the way your home heats. 

All of that air going up the chimney regardless of whether it was used by combustion or if went up the chimney in between burner cycles needs to be replaced somehow.  Usually this occurs when the chimneys pull the home into a slightly negative pressure and causes drafts through the doors and windows of an older leaky home.  On a cold day this infiltration of outdoor air exacerbate any comfort issues in the home. 

TerrS

Please don't focus on the fireplace, and back to my original question. What are my downfalls if I ran 2 thermostats to the same system? Besides w/o zones, I would be heating the already warm downstairs.

I think, but still in progress if I insulate better it will only exasperate this issue. Meaning if the boiler doesn't run. Then no heat produced. T-stat in dining room controlling all the heat in the house.

Even without the fireplace, let's say I am cooking Thanksgiving dinner. And the oven is on for 5 hours. It heats up the kitchen which is right next to the dining room and then causes the same issue.

Btw TRV's are not an option on fins, because there is no bypass.

WMno57

TerrS said:

I understand without zone valves to control were I will be sending the heated water, that my first floor might become over heated, if the 2nd floor calls for heat, that just means that my fireplace would probably not run as much if this happens.
Is there a better alternative?

The better alternative is to have one, and only one thermostat on the second floor.
Did Ray come out to your home?

WMno57

@terrs, I want you to think about something. Your fireplace requires air for combustion. Where does that combustion air come from? Where do the combustion byproducts (Carbon Monoxide) go?

TerrS

WMno57 said:

I understand without zone valves to control were I will be sending the heated water, that my first floor might become over heated, if the 2nd floor calls for heat, that just means that my fireplace would probably not run as much if this happens. Is there a better alternative?

The better alternative is to have one, and only one thermostat on the second floor. Did Ray come out to your home?

Yes. He was actually great, but doesn't do residential houses, but was willing to help and advise me.  So he took all my information, boiler sizing, etc.

He responded back to me last night and told me my boiler seems to be running on par with output expectations. He also stated it takes 20-30% additional Btu's to heat all the cold pipes in my house, so my boiler is actually slightly undersized. Given 2000sq ft. He estimated 30 gallons of water circulating, even though I think that's high, he has a commercial used program he wrote to calculate btus transfered to water over time and sent me a pdf. And it showed it calculated 30 minutes for 168 degrees water, so my 40 minutes is in-line with getting to 180degrees.

So I asked him if he could give me any recommendations. Waiting for a reply. Also found out my old boiler is only 75% efficient, so even staying with a non-condensing boiler I would get a 10% boost if I upgraded to a newer boiler.

He like others have softof said, they want my boiler to run more, not less. That would reduce or help my cold starts. Ie 64 degree water to 168-180 water is less time/energy, if I am starting at higher residual temperature like 90-100 degrees. That comes at a cost.

So once again I was back to, I can add all the insulation in the world to my 2nd floor, but if the boiler doesn't run because the first floor is warm and happy. I haven't solved a thing.  Yes I would retain the heat longer when the boiler did fire, but still doesn't solve if it's colder and wants heat

TerrS

WMno57 said:

@terrs, I want you to think about something. Your fireplace requires air for combustion. Where does that combustion air come from? Where do the combustion byproducts (Carbon Monoxide) go?

Yes the room, my house will never be totally sealed ever, 1903 vintage. So the air moving/circulating is enough that my fireplace releases as much as a oven running

WMno57

When you light your fireplace you create a partial vacuum in your home. This draws MORE air through all the cracks creating drafts. You feel cold. You turn up the fireplace. More drafts. Rinse and repeat.

pecmsg

TerrS said:

WMno57 said:

I understand without zone valves to control were I will be sending the heated water, that my first floor might become over heated, if the 2nd floor calls for heat, that just means that my fireplace would probably not run as much if this happens. Is there a better alternative?

The better alternative is to have one, and only one thermostat on the second floor. Did Ray come out to your home?

Yes. He was actually great, but doesn't do residential houses, but was willing to help and advise me.  So he took all my information, boiler sizing, etc.

He responded back to me last night and told me my boiler seems to be running on par with output expectations. He also stated it takes 20-30% additional Btu's to heat all the cold pipes in my house, so my boiler is actually slightly undersized. Given 2000sq ft. He estimated 30 gallons of water circulating, even though I think that's high, he has a commercial used program he wrote to calculate btus transfered to water over time and sent me a pdf. And it showed it calculated 30 minutes for 168 degrees water, so my 40 minutes is in-line with getting to 180degrees.

So I asked him if he could give me any recommendations. Waiting for a reply. Also found out my old boiler is only 75% efficient, so even staying with a non-condensing boiler I would get a 10% boost if I upgraded to a newer boiler.

He like others have softof said, they want my boiler to run more, not less. That would reduce or help my cold starts. Ie 64 degree water to 168-180 water is less time/energy, if I am starting at higher residual temperature like 90-100 degrees. That comes at a cost.

So once again I was back to, I can add all the insulation in the world to my 2nd floor, but if the boiler doesn't run because the first floor is warm and happy. I haven't solved a thing.  Yes I would retain the heat longer when the boiler did fire, but still doesn't solve if it's colder and wants heat

Wrong
Wrong
Wrong

WMno57

I recall you said a couple months ago you planned to move in the next few years.
Put carpet on the attic floor, or insulate.
Relocate thermostat from first floor to second floor.
Done.

Jamie Hall

WMno57 said:

I recall you said a couple months ago you planned to move in the next few years.
Put carpet on the attic floor, or insulate.
Relocate thermostat from first floor to second floor.
Done.

This

TerrS

WMno57 said:

I recall you said a couple months ago you planned to move in the next few years. Put carpet on the attic floor, or insulate. Relocate thermostat from first floor to second floor. Done.

Yes and no, that is a 5 year window and many many things can happen in that timespan. Just putting carpet will not solve the issue, because cold air is still between the floors because of house design and knee walls have access to the roof.

So I am addressing that with insulation next week in all the ceilings on my 2nd floor and 2 small walls that were never insulated. Plus I am looking to spray insulation on my rim joist and outer foundation as to stop air penetration in areas I know are colder.

And lastly probably move my t-stat because that seems to be the only way to let my upstairs call for heat

pecmsg

Are there T-Stat wires already pulled to the 2nd floor?

TerrS

pecmsg said:

Are there T-Stat wires already pulled to the 2nd floor?

That is a 1hr fix and 40ft of wire. So there could be quickly.

KC_Jones

TerrS said:

WMno57 said:

I recall you said a couple months ago you planned to move in the next few years. Put carpet on the attic floor, or insulate. Relocate thermostat from first floor to second floor. Done.

Yes and no, that is a 5 year window and many many things can happen in that timespan. Just putting carpet will not solve the issue, because cold air is still between the floors because of house design and knee walls have access to the roof.

So I am addressing that with insulation next week in all the ceilings on my 2nd floor and 2 small walls that were never insulated. Plus I am looking to spray insulation on my rim joist and outer foundation as to stop air penetration in areas I know are colder.

And lastly probably move my t-stat because that seems to be the only way to let my upstairs call for heat

Your second floor can't call for heat.  The thermostat, regardless of position, will call for heat for the entire house.  You are always heating the entire house.  So no matter where you put it, the entire house is what is always calling for heat.  The only way a specific area can call for heat is with zones, period.  If you have imbalance, that has to be fixed in the piping through flow control.

Moving the thermostat is a fools errand.  Want the second floor warmer without changing any piping?  Go to it right now and turn it up to 73-75, the second floor will then be 68, based on the data you have given.  If you move it upstairs and set it to 68 the downstairs will be 73-75, even warmer if you run the fireplace.  So no matter how you slice it you have an imbalance in the house.  It has nothing to do with thermostat position at all.  Again, thermostat is just a switch, it's on or it's off, that's it, nothing more.

You need more flow upstairs and less flow downstairs.

TerrS

@KC_Jones okay I get that, and like I stated, the fireplace would probably run way less.

So not that I want to open yet another can of worms, but Ray just responded and he states my pump is moving my water thru at 17gpm, yikes.  I have enclosed a pump picture can anyone else verify. So adding zones would only exacerbate this even more and cause other issues. Could this also be not letting the emitters to radiate the heat properly? I mean most fins are rated between 1-4 gallons.

And not that I even understand how flow is determined. But he stated I am 50% over sized and for a 170k boiler.

TerrS

Couldn't attach to my reply for some reason

Robert_25

That circulator will put out 17 gpm with no resistance.  That is not the case, since you have the resistance of the piping, radiators, etc.  I not would expect that circulator to be oversized.

what have you done to balance the system? The first thing I would do is throttle the flow to the first floor.  

KC_Jones

TerrS said:

but Ray just responded and he states my pump is moving my water thru at 17gpm,

Ray needs to learn how pump curves work. Unless you have zero head (you don't) there is no way that pump is moving the water at 17 GPM.

TerrS

@Robert_25 so my only options are to turn my ball valves on each zone off alittle on some. My weekend project is to fire up my boiler with all but one zone open. And determine where that pipe/zone feeds. Then open another until I know them all. That's the only way I could balance with anything currently installed/available

hot_rod

For anyone to say the boiler is undersized, or correctly sized, an accurate room by room heat load calculation would be required

So far all we know is boiler size, approx efficiency and connected radiation sizes

No amount of thermostat “trickery” can solve the issues you are concerned with. I think will will just frustrate the situation with a two thermostat attempt for a single zone?

wait and see if the steps you have planned to seal and insulate help enough.

Robert_25

TerrS said:

@Robert_25 so my only options are to turn my ball valves on each zone off alittle on some. My weekend project is to fire up my boiler with all but one zone open. And determine where that pipe/zone feeds. Then open another until I know them all. That's the only way I could balance with anything currently installed/available

What type of radiators do you have on the first floor?

TerrS

Robert_25

What type of radiators do you have on the first floor?

All fins. But there was a buderus 3' rad and k120 kick in the kitchen. With a 35% flow thru and 65% bypass to feed fins down stream. Also a 20" buderus rad in my bathroom, same bypass

Robert_25

In addition to balancing the flow through the various loops, you can also close the dampers on the fin enclosures.  This will take some trial and error, but you should be able to reduce your heat output on the first floor and possibly increase it on the second floor. 

TerrS

@Robert_25 thanks,  so I am going to apologize 100 times over, if I ask something twice but I probably didn't understand the answer.

@hot_rod stated many times, try and seal my house as much as is possible or money will allow. This then gives me a better starting point for my heat loss.

But here is where I don't understand. Is there a way to determine my water flow is thru my fins? Yes the pump is rated at 17gpm without restrictions. So I see a 1.25" coppet pipe off the manifold into the pump, but the pump looks like it's 3/4" opening. So no bottleneck. Right? the water would going thru as fast as the pump will go because it's sitting in that manifold.

Let's hypothetical say its even restricted by 50%, that's a flow rate of 8.5gpm??? And for my fins to be most efficient, should be around 4ish GPM?

What am I missing?

ChrisJ

I use a Honeywell Prestige with 3 indoor sensors, all of which including the thermostat average the temperature in 4 areas to control 1 boiler.

I then, in my case have 5 TRVs on steam radiators which throttle radiators if areas are warmer.

That being said...
I've also known quite a few people who heated 2 story houses with nothing more than a properly placed woodstove and some behavior changes like living doors open etc.

TerrS

@KC_Jones so please help Me here.

So 141ft of total fins spread across 4 zones.

So for as much as I know and rough figures, 141ft plus the kick plus the 2 rads, equals around 104k btus.

Using a standard formula of 1gpm = 10k btus. I divide my 104k and get around 10.4gpm thru my 4 zones.

Let's consider them equally balanced for the moment, which is 2.6gpm, it's probably more like 3.3, 2.4,  2.4 and 2.4 but simpler to calculate. Anyhow...

Next and in looking at my copper pipes, I am using mostly all type M, at 3/4" but I do have 1 run at 1", but let's make this simple for a second. Let's figure the pressure drop/friction from 541ft of 3/4 copper with fins .0009 at 3gpm(2.6gpm actual) (type m) x 541ft = is around .5ft head pressure????

So my pump is way over-sized?

Did I do that right?

My bolier output is 113k btu it could provide. So it's close to my calculations. This is using information I learned from Ray and using a tape measure.

The real unknown is what is my real room heat loss calculation. But adding in what ray stated of 20% extra btu's required for that 400ft of supply/return lines, puts me at that 113k boiler output number, so things are starting to make better sense.

So is the pump not allowing full radiation of the heat actually being produced???

Jamie Hall

The pump is going to pump what it is going to pump -- but that varies with the pressure drop. More pressure drop, less flow, and vice versa. That relationship depends on the type of pump, and is expressed in the "pump curve" for the pump.

At the moment, as it stands, you don't have any real idea what either the pressure drop the pump is working against or the flow is, so any figuring on that is out.

What you do know -- I hope -- is the temperature of the water going into the various emitters -- radiators and what have you -- and the temperature coming out. There are tables for the various type of emitters which will give you the BTUh output of the emitter, based on the average water temperature in them.

You basically have a balancing problem, and you can do arithmetic all day and not get anywhere. What you do need to do is to find a way to either restrict the heat output of the emitters in the spaces which are too hot, or reduce the flow rate by throttling a convenient valve to those spaces -- and fiddle with both of them until you are happy with the result.

TerrS

@Jamie Hall yes but that's the issue and has been, my water is 180 degrees and using a 4gpm or 1gpm fin heat output. It's around 600-625btus per ft at those gpms.

So if you start asking, are they really giving off those btu's.  I start asking how fast is my hot water moving.

ChrisJ

TerrS said:

@Jamie Hall yes but that's the issue and has been, my water is 180 degrees and using a 4gpm or 1gpm fin heat output. It's around 600-625btus per ft at those gpms.

So if you start asking, are they really giving off those btu's.  I start asking how fast is my hot water moving.

There's literally no way your water is always 180F and 180F at the input and output of every radiator.

pecmsg

TerrS said:

@Jamie Hall yes but that's the issue and has been, my water is 180 degrees and using a 4gpm or 1gpm fin heat output. It's around 600-625btus per ft at those gpms.

So if you start asking, are they really giving off those btu's.  I start asking how fast is my hot water moving.

Are you ASSUMING or measuring?
you also need water temperature in and out. 

TerrS

ChrisJ said:

 

There's literally no way your water is always 180F and 180F at the input and output of every radiator.

Yes it is, or close to it. Prior to me putting the Beckett 7610. My water was always 180-185, and the differential was like 5 degrees. Now it's gets adjusted dynamically by the built-in heat Manger.

I am guessing my next purchase is a clamp-on temperature Guage to prove who's right?

My hand can't really tell the difference between 180 degree water and 170 degree water, but you are not holding on to them for long.

HomerJSmith

To get back to the original question--running one zone (two floors) off of two thermostat, you can be sure that one or the other floor is going to be incorrect temperature wise because only one thermostat can effectively have control.