Baseboard heating - our house is really dry and I am trying to figure out why

JUGHNE

Your BB heaters are really convectors, air must flow thru them to deliver the heat needed in the room. If that convective air flow is blocked for any reason.....dirt, lint etc... then the convector turns into a radiator. But is woefully too small to be a proper radiator for the job. Some BB have a linear flipper door on top to reduce the air flow thru is to reduce temp in that room.

With 200* water the air flow should move say a single paper hanging on the wall. Or make a tissue flutter.

Some elements of BB may get installed wrong, that is twisted 90 degrees to where the fin openings run horizontally rather than vertically. This would almost stop the convection. Hard to imagine the entire house done that way.....but things happen...some people do things consistently wrong for the entire job. FWIW

Steve Minnich

@adam061712 - "I have no idea why the house has to use 200 degree water. As I mentioned the guy that services my boiler discovered that it was set to 220 and turned it down to 180 and we could only heat the house to 66-68 degrees so now it is up to 200 and we can get to 70-72"

The "guy" that serviced your boiler that one and only time is me - Stephen Minnich of Minnich Mechanical Design. You had no heat and I was there within hours to replace a defective gas valve. The boiler was diagnosed and repaired within 45 minutes. I am also the "guy" that quoted the Aprilaire 350 humidifier because you asked me too. I am more than capable of diagnosing and/or solving any hydronic, SpacePak, or humidity issues that you currently have. There has been a lack of trust here that I can't fathom because I'm as honest as the day is long.

ChrisJ

Stephen Minnich said:

@adam061712 - "I have no idea why the house has to use 200 degree water. As I mentioned the guy that services my boiler discovered that it was set to 220 and turned it down to 180 and we could only heat the house to 66-68 degrees so now it is up to 200 and we can get to 70-72"

The "guy" that serviced your boiler that one and only time is me - Stephen Minnich of Minnich Mechanical Design. You had no heat and I was there within hours to replace a defective gas valve. The boiler was diagnosed and repaired within 45 minutes. I am also the "guy" that quoted the Aprilaire 350 humidifier because you asked me too. I am more than capable of diagnosing and/or solving any hydronic, SpacePak, or humidity issues that you currently have. There has been a lack of trust here that I can't fathom because I'm as honest as the day is long.

I can't blame someone that knows very little about HVAC to have trust issues with anyone they don't know.

That said, to the OP, Stephen Minnich isn't your typical HVAC guy. He's a good man and does good work. Not to mention, he comes on here and helps others with problems when he can for free. That says a lot IMO.

Brewbeer

@adam061712, you need to take the covers off the baseboards and clean them. They do get dirty, especially along the bottom. Compressed air works best if you have it, a vacuum and brush if you don't.

Gordy

I don't think 30% rh is bad . Mine is that with out intervention no nose bleeds. I have the worlds most accurate hydrometer ........my wife. Oh yeah I'm Italian big schnozzola.

ChrisJ

Gordy said:

I don't think 30% rh is bad . Mine is that with out intervention no nose bleeds. I have the worlds most accurate hydrometer ........my wife. Oh yeah I'm Italian big schnozzola.

I think their bed is too close to the baseboard.

adam061712

@Stephen Minnich and everyone else. The question was asked by @Gordy "why does your house have to be 200 degrees?". I simply answered the question.."I don't know". and that is the truth. I don't know why. I am not a boiler professional so I don't know the rationale behind it. For whatever reason my house has to heat the water more than 160-180 degrees to 200 degrees in order to reach 70-72. In that comment there was no judgement of @Stephen Minnich or his work. I was just answering the question of, "why does it have to be so high?" I was just providing the answer to the question as best I understand it. I am not sure how that statement was interpreted as me not thinking my contractor was reputable guy. I actually have found @Stephen Minnich work to be great. He has been super honest with me about everything but he also doesn't live in my house and can only solve the question as good as the information I provide. I never implied anything otherwise not sure how it got interpreted that way. I am just trying to be good consumer and understand what is going on with my house so therefore I ask questions and answer the questions that are provided to me with what I know.

adam061712

And lastly yes @Stephen Minnich was at my house to fix the problem super quickly. I never questioned that or mentioned that I was unhappy about that or that I ever thought the situation was handled improperly. I was actually very appreciative of that and thought it was handled great in a really timely manner. I have and always have felt that @Stephen Minnich was doing what he thought was best for my house. I have no idea how this was interpreted as me questioning his work. However, I do question everything any contractor recommends. I think that is being a good consumer and making sure you (the consumer) spend you money wisely.

bob_46

I am pre mod/con . In the 60s and early 70s IBR recommended 200º as a design temperature. Some mfg. recommended 210º (Triad). I've often wondered what happens when a mod/con is installed as a replacement boiler on these jobs. From what I understand some of them can't supply water over 170º.

ChrisJ

adam061712 said:

And lastly yes @Stephen Minnich was at my house to fix the problem super quickly. I never questioned that or mentioned that I was unhappy about that or that I ever thought the situation was handled improperly. I was actually very appreciative of that and thought it was handled great in a really timely manner. I have and always have felt that @Stephen Minnich was doing what he thought was best for my house. I have no idea how this was interpreted as me questioning his work. However, I do question everything any contractor recommends. I think that is being a good consumer and making sure you (the consumer) spend you money wisely.

TERRY1

Interesting reading. A lot of good information.

JUGHNE

Bob, that got me looking at the IBR book from 1988. It sounded like the push for higher temp was to reduce the amount of connected BB. "AWT of 170* will require 60% more connected BB than AWT 215*" also...... "215* would only use 3 more gallons of oil per year than 170*"....."high design temp is practical and common in US & Canada" Apparently they were trying to compete with forced air by reducing the installation costs.

I can see that a ModCon would be challenged to provide this temp, let alone produce its rated efficiency. If the building envelope was greatly improved perhaps lower temp would work.
But don't guess the ModCon would shine much more than CI.

So I relearned something I was exposed to in 1990, as these points were underlined by me in the book from that class.

Gordy

Hatterasguy said:

Gordy said:

I'm asking the question for discussion Chris. But emitter type must play a role. High temp verses low temp.

If 75% rh 10 degree cold air infiltrates into a 70 degree envelope that same air rh becomes 7%.

If your indoor temp is 70 degrees 40% rh, and that air goes over a 180* emitter the RH drops significantly to 3%.

If you are the same 70* 40% rh with an 80* emitter the rh drops to 30%.

Go to the link and play with scenarios. Go to the bottom to the relative humidity calculator.

Here's the better way to look at humidity levels in a building:

The air outside the building has a certain water content in PPM. At colder temperatures, that air, with exactly the same water content, will show a higher relative humidity as the cold air cannot hold as much water as warmer air.

Since we focus on relative humidity, the entire discussion gets confusing to folks because. as you heat the air, the relative humidity drops even though the moisture content remains identical.

If the air has a certain quantity of water when it's outside the building, it has the exact same quantity of water when it warms up inside the building.. However, the relative humidity, which is simply a measure of the capability of the air to hold water will drop.

Relative humidity is a measured quantity for humans as the lower the relative humidity, the more capability the air has to extract moisture from the human and the more uncomfortable the human becomes when the relative humidity drops quite low.

The argument that more infiltration lowers the RH in the building is valid in most cases for the following reason:

If the building is sealed, the RH is going to climb due to evaporation from the humans within the building and from generalized use of baths and showers. The effective RH will be higher than the RH obtained if the outside air is heated to the indoor temperature. Therefore, as the infiltration is increased and that air is heated, it dilutes the existing air and lowers the RH slightly.

If you were to remove the humans from the building and have no capability to increase the moisture content of the indoor air, the RH in the building would be constant, independent of infiltration losses. This must be the conclusion as the actual water content of the air in the building must be the same as the actual water content of the air outside the building (as the walls are permeable).

Agreed.

That is what the calculator is for I posted. What it does not do is give a mixed RH of what the air brought inside from outside would end up reducing the indoor RH by.

As I said earlier I don't discount infiltration. But there is other things in the mix. Or I just live in one hell of a tight 50's construction house. Don't believe that either. Lots of glazing. All though I do believe my exterior wall detail is very tight.

I go back to high temp emitters. Add convection.......nosebleed.

SWEI

Not sure of the math behind it, but http://go.vaisala.com/humiditycalculator/5.0/ does provide PPM outputs -- both by volume and by weight.

ChrisJ

Hatterasguy said:

Thanks for posting that. Extremely valuable.

For ambient air at 20F, with a 50% RH, the water content is 1843 ppm.

If that same air is heated to 70F (independent of method), the water content remains the same and the relative humidity drops to approx. 8%.

A typical residence might have RH in the range of 20% under such conditions, thereby reflecting the contribution from the humans and the hot water usage.

The greater the infiltration loss, the lower that 20% figure becomes. In a house with extreme infiltration losses and not many humans, the number could drop to near 8% (the calculated value without any additional moisture from within the building).

Not to mention how incredibly inaccurate most hydrometers are. I have 3 in my livingroom and it's pretty sad. I've often seen them 10% apart. It seems most don't even give you a specification on their accuracy but I wouldn't be surprised if it's +-10%.

I've considered buying a good sling psychrometer but it's one of those things that's never really mattered enough.

SWEI

Decent humidity sensors cost money. The incremental cost to add a humidity sensor to the stats (room terminals, really) for our DDC platform is almost $50.

ChrisJ

SWEI said:

Decent humidity sensors cost money. The incremental cost to add a humidity sensor to the stats (room terminals, really) for our DDC platform is almost $50.

$50?
What's the accuracy of that sensor?

SWEI

Specified at +/- 1.8% RH.

Gordy

High temp emitters bad.......

ChrisJ

Gordy said:

High temp emitters bad.......

Yeah,
I knew that's where you were going with this from the start.
I shouldn't have even bothered................

Gordy

Let's put this in perspective. If lower temp outside air is brought into the conditioned space dragging RH down. Then the normal room temp air at its RH is dragged across a hot emitter then RH has to drop in that vicinity of the emitter. Remixing with room air to equalize back. However if you sleep next to an emitter then you are going to be exposed to that lower RH air during heating cycles through out the night.

As the temps drop outside, cycles increase with the heating system thus compounding the effect.

I'll bet if you put a decorative tray of water on every rad you would notice a big difference. I will also bet that if you put identical volumes of water on the emitters, and one away from the emitters on a table or what ever the emitter ones would evaporate first. Hard to do with baseboards.

ChrisJ

When I was running my humidifier last winter, it was dumping 10 gallons into the air every 24 hours and only maintaining 35% RH.

I promise you, putting bowls of water on my radiators will be meaningless.

Gordy

Not really. Just have to get bigger bowls moisture in air is just like hot to cold. It's equalization is not instantaneous though. So if you humidify next to the points of lowest humidity you will speed up the process. Maybe even go through 20 gallons.

Gordy

Think about it like this. Where are rads usually located? By a window. Where would infiltration be highest? Probably by the window if old ones, and not very tight. Infiltration in this region is more intense especially when the rads are at peak temps. So RH would be lowest. Your dumping humidity where it is theoretically lowest the point of infiltration.

BobC

@ChrisJ @SWEI Back when I ran an environmental lab for NAVMAT testing of military power supplies we needed a good method of measuring humidity to make sure we were meeting the test specs. The Associated test chambers we used were known to be less than stellar when it came to their RH measuring abilities.

We took a thermocouple and draped a piece of cotton over it that was draped into a small jar of water, that was our wet bulb. A second thermocouple was used as the dry bulb. A 100 CFM muffin fan was used to move air across both thermocouples.

It was an easy cheap way to measure RH and it was repeatable.

Bob

Mike Thomas_2

The bower test is your only solution. But you really need more. You need someone who does blower door testing with weatherization. During a blower door test, the biggest leak will show up. You fix that one, and then the next biggest leak shows up, you fix it, and so on and so on. If you just invite someone to do the blower door test, you will have to invite them back, after you fix the first leak to find the next.

We have done lots of blower door tests and weatherization. It sounds like your leaks are going to be up near the ceiling. If you don't feel drafts, the leaks are probably up high. The hot air is rising and coming in the bottom, probably at the sill plate.

The weatherization with blower door test will cost considerably less than what you paid for those windows.