Dehumidifier for forced hot water by oil heater

First off let me say that your heating system has nothing to do with your mold issue unless it is leaking some where that you dont know about.If anything your heat plant should be lowering the humidity, bc of the air is expanding causing the number of grains of water vapor to occupy a larger volume of air.I can only assume that your son envelope is very tight which mean not only does he have a need for a dehumidifider but maybe some fresh outside air to lower the co2 in the home.Do a search on santa fe dehumidifiders.Go to their site and do some research it should help you with dealing with your son issue.

Is the humidity an issue in the summer or winter?

One thing to consider is a whole house ventilating dehumidifier. It will dry the house year round. Even if you have A/C, there are a lot of times it is humid but not warm enough to have the A/C run enough to keep humidity under control. And you certainly don't run the A/C in the winter. The ERV/HRV works in the winter by bringing in outside air and recovering heat from the exhausting air but won't help humidity control beyond cold weather. The dehumidifier will lower the humidity year round. Many have the capability of a damper that opens usually timed to bring in fresh outside air and have it dehumidified before put into the house.

http://www.forwardthinking.honeywell.com/related_links/dehumidification/50-1018.pdf

Are there exhaust fans in the baths and kitchen? If so, are they used appropriately? Is the foundation damp? Is laundry being line dried indoors?

Icesailor, minisplits and other variable-speed cooling is much better at humidity control than more old-fashioned slam-bang cooling, but it is no substitute for a dedicated dehumidifier in my experience. I always run a dehumidifier in times of high humidity when there is little need for heating or cooling. The mini splits still cool significantly in dehumidify mode. Sometimes I'll run one mini split in the house with the dehumidifier running or it gets too warm, sometimes not.

Search for 'ductless mini split' and you'll see an entire range of options. They are by far the most common systems in much of the world.

@bio_guy:

bio_guy said:

Are there exhaust fans in the baths and kitchen? If so, are they used appropriately? Is the foundation damp? Is laundry being line dried indoors?

Icesailor, minisplits and other variable-speed cooling is much better at humidity control than more old-fashioned slam-bang cooling, but it is no substitute for a dedicated dehumidifier in my experience. I always run a dehumidifier in times of high humidity when there is little need for heating or cooling. The mini splits still cool significantly in dehumidify mode. Sometimes I'll run one mini split in the house with the dehumidifier running or it gets too warm, sometimes not.

That's true what you say. But I lived in a place at the ocean where it wasn't that hot but the humidity would kill you. People moved into their cellars and rented out the upstairs, or rented the cellars. At a 70 degree OAT, and a 70 degree dewpoint, a cellar is unlivable. So, they get some type of de-humidifier and pump the waste water into another place, maybe a dirt floor. But the waste heat for compression made the room even hotter. So they let the cooler moist air in. You understand the issue?

I did a brand new house with radiant in the ceilings. No AC. The two boys lived in the cellar. They would come home late at night and the finished basement was so hot that they opened all the large windows. A large puddle of water appeared. They insisted that there was a water leak in the ceiling. The closest water was 20' away. With the window open at night, the cool moisture laden air came through the open window and down the outside stairway, hit the cool tile floor, and condensed into water. I convinced them to put in a Mini-Split because a throw away dehumidifier would give off so much heat that the room would be hot, and they would open the door and windows again. I installed the Mini-Split and that was the end of that.

I don't make this ship up. I lived it. This place (heatinghelp.com) makes me remember so many crazy things I have been in to. If there's a problem, someone has to fix it. It might as well be me so I can learn something.

HVAC person, but not just any HVAC person. You want someone factory trained on the specific brand and model line you specify. Lineset purging, evacuation, and charging are critical on these newer systems, and the controls are all different.

I live close to the Canal, and run a dehumidifier year round, Way of life near the water

Barbarapratt, I am sorry that we are getting kind of far from your problem.

A mini split is not what you want to do if you are humid in the heating season in what I would call the NE. A house normally ranges from dry to too dry under those conditions. I am working with limited information, but I feel that something is wrong with that house. (What are the indoor and outdoor temperature and humidity levels or what is the climate like where the house is?) In cold weather a dehumidifier is a better bandaid than a mini split. Note that any HVAC solution to this problem is probably a bandaid so if you are going to get a dehumidifier, an inexpensive one would be a better choice for a short term while you are figuring out what is really wrong.

I think that you need to have your house evaluated by an expert to find out where the humidity is coming from. That damp foundation is a prime suspect. If the soil around the foundation is water-logged, I hope that it can be trenched and tiling an pipes set up to drain it. Moisture proofing and sump pumps on the inside are not as good an approach, but might work.

Again, find an expert to help you figure out how to dry your house. High humidity levels will damage the house and can damage your health as fungus levels grow. In the meantime, get a couple of inexpensive electronic hygrometers, check them against each other and then start monitoring the relative humidity levels in the house and report back here.

You might start with your local home inspectors. I'd start with the largest ones that have both engineers and energy experts on staff. The bigger they are, the more likely they will have a person with specialized knowledge needed to figure out the problem. Call a number and interview them over the phone to see how they respond to the issue before you hire one. I'd start with some real data from the house. How humid is it? You'll go nowhere without defining the problem.

Not only do you look at the inside of the building envelope you also look at the outside as well.we have lots of crawls in my area where drainage going away from the home as been screwed up do to all the high flower beds around the home.that water puddles then head down hill into the crawl.off topic,went to a home last week the guy was doing some work in the home.had all the windows open and a torpedo heater going.all the walls inside the home were sweating n beads of water running down them.hmmm who were have thought that would happen.lol

Home inspections will never find all the problems all of the time. You just have to hope that they will find the serious and expensive ones. When they can't find a real problem, they nit pick to justify their presence.

For the OP, winter with sustained high indoor humidity in a heating environment is unusual in almost any situation. This makes it an emergency: "They are beginning to have mold problems". In the short term, get a dehumidifier or two before you have serious damage to the home. An even faster way to reduce the moisture is to ventilate as long as the absolute humidity is lower outdoors compared to indoors. Just open some windows. Identify the source of the problem before investing in an expensive remedy like a central dehumidifier.

For dehumidification and summer cooling, mini splits are certainly something to consider. I love all seven of mine and I ditched an existing duct system to get there. Efficient central dehumidifiers make less heat than common portables. Increased efficiency in moisture removal means less heat by nature. Efficient portables can be had from the same manufacturers as the central ones. The Energy Star web site rates them in liters/watt.

Coastal MA, been there and done that, but only in the Summer ca. Woods Hole. I am in South LA for several years now. I am not sure where is worse for humidity alone. For the combination heat and humidity, I do know. The coastal plain in the NE USA is very underrated as a noxious environment. After growing up in beautiful upstate NY (Nearer the North coast than the East coast), I was introduced to not only sustained higher humidity, but also poison ivy, ticks and chiggers on and near the East coast.

As another note, since living in South LA, I've come to appreciate that the air is much richer source of moisture than the ground, even when the latter is quite damp. With a cool structure and a high dew point and relatively fast moving air (relative to slow moving soil), you get fantastic moisture transfer rates. Old houses retrofitted with mechanical cooling and the requisite outdoor duct systems wreak condensation havoc. That is especially true because the ducts always leak and turn the duct systems into power vents drawing in moist, outdoor air in negative pressure areas.

A lot of good ideas here but in the meantime I'd plug in a dehumidifier.