Cast iron hydronic rads would be a good choice. Do you have any? Buderus oil boiler would also be a good choice, gas would be better.

SR

cast iron hydronic radiators: any brands stand out?

boiler is still doing well so we will keep -- and no local Buderus guys (we understand that it's a great boiler but happiness depends upon installer and good ones are few)

Gas is not available here and propane is 1 1/2 x oil so no go.

It’s not that simple. A hydronic system with emitter (radiator) selection has to be properly designed if you don’t already have one and not just thrown together.

You should start with a company that can then do a proper room-by-room load calculation and then size the emitters based on the design of the plumbing (primary secondary reverse return loop, series connected, water temperature, zoning etc.). Primary secondary loop properly designed will mean that all the emitters will receive the same water temperature. Series will mean that the last emitters receive the coldest water just before returning to the boiler and therefore have to be sized accordingly, as in MUCH larger.

This is not something to be guessed at but properly designed for comfort and efficiency for your area’s design conditions.

IMO

SR

We have a 1940 home with the original radiators and a one year old Buderus gas boiler. Heating is very smooth, and based on the gas bills its also very efficient (boiler is rated at .84).

I don't know if new radiators hold heat as well as the old ones we have, but that smooth heat retention seems to be why the heat is so pleasant. It is much better than the heat/no-heat feel you get with forced air.

I have also found many folks who never used radiators don't really understand that the cast iron in a hydronic radiator is not that hot. It can't start anything on fire, and it has such a large radiating mass that even at 140-150 degree water temps the kids find it easy to sense the heat and take their hand off the radiator if its too hot for comfort. Its not like a hot frying pan or stove burner where the heat on your hand builds so quickly that you can't draw away fast enough.

Bruce

I had hot water radiator heat for several years where I lived when on a work assignment in a different area. I hated it, mostly for two reasons.

1) There always seemed to be a wide range of temperature in the rooms, as with a fireplace. You'd be warm or too hot when near to the heat source but chilly or even cold when on the other side of the room.

2) I like to sleep in a cool house overnight. After turning the heat down, the recovery time to a normal temperature in the morning took hours and hours. Way too long. Maybe it wouldn't be a problem for you if your place is small and you keep the heat on at night.

Forced air heat is what I like. The air movement makes for more uniform temperatures.

OP seems to like the heat radiated from wood-burning better than baseboard that is mostly convective heat transfer. Will a heavy wall-mounted radiator mimic that? Mass will even out heating. Certainly sitting or standing near a wall radiator will allow you to feel the radiated heat more than baseboard. If you like that effect, you can run your radiators at a relatively high temp and install few of them. That way you might have the effect of feeling warm on one side and cool on the other. It won't be like a fire, mind you. It won't be a very efficient system either.

Snidley, I've been in a lot of hydronic radiator homes and never noticed uneven temps across rooms. Typically, the radiators are under windows and otherwise outside walls. Maybe your system had radiators on the interior walls.

Fast warm-up is a characteristic of capacity. An oversized system is always going to warm up quickly whether forced air or hydronic. In a household with no one home on most days, that likes to set back the temp at night, more capacity might be a good thing. There seems to be very little consideration of the lifestyle of the homeowners when designing HVAC systems. In this day and age, I suppose, that might not be so bad since people trade houses so much compared to past generations.

The radiators were all under windows with stone (maybe marble?) sills that seemed to do a good job of absorbing head rising from the radiator and releasing it gently whether the system was on or off. Thinking about it, I remember during warmup periods the system would overrun the set temp, so if I wanted the place to be 68, I needed to set it to 65. Then sometime after the system clicked off, it would continue heating to several more degrees of gain. I then would need to then raise the thermostat setting to perhaps 67 or 68 so that the next on cycle wouldn't be delayed. All this hassle in a location that had winters colder than I was accustomed to but otherwise mild - highs in the 40s, lows in the 30s.

Yes, give me gas forced air.

Thanks for the feedback. I am familiar with cast iron radiators from my youth. Outstanding for drying mittens :-)

From the weights of the Buderus radiators I doubt they are cast iron. I was hoping for someone who owns them to be able to give a report as to how they performed against the cast iron ones.

What I don't care for about the baseboard heat is the hot air. I have asthma and find it very difficult to breathe when I get it hot enough (74 degrees) for these old bones. It is not as bad as forced hot air but still, the air feels thick when I crank up the baseboard. With the wood stove, the heat was intense near it but the air away from it was breathable and I remained toasty because things (furniture) warmed up. I was hoping for a similar effect from the radiant heat of the Buderus but didn't know if non-cast-iron would be pleasant.

Do you have a hygrometer in the house? What are your winter temperatures like?

I think that you need a humidifier. If your wood heat is not externally vented and you stop using it, your indoor humidity will increase. A well-sealed house has better humidity control throughout the year.

ionized, could you take it down a notch for those of us who are heating challenged? When burning wood there was always a large pot of water on the stove to add humidity.

A new bathroom fan which has a humidity sensor is due to go in next month. Because the cottage is tiny, it will really ensure the whole place stays mold free.

Are you saying we should set the sensor high so the heat feels/breaths better?

House is a retro remodel and we are ancient arthritics but we have air sealed attic and insulated, insulated crawlspace & put down liner on earth, opened crawlspace to basement so boiler keeps downstairs temp @ 68. Last is new windows with air sealing exterior walls as best we can. It won't be a Passivhaus, but it is good enough for our last years.

I'm just trying to decide between baseboard heat and radiator heat for the coziest feel. I'm sort of lost about the humidity.

OK, I'll try. I am not asthmatic, but I still feel stifled when the humidity is too low in hot rooms. My nose seems to close up for the dry air. I hope that the following helps to clarify some of what I previously wrote.

When it is cold outside and you are heating, you can have relative humidity inside that is too low for comfort. The first step, or me, is awareness. I'd advise you to get a couple of inexpensive electronic hygrometers. (Two so you can use one as a check on the other.) The figures that are usually given for comfort and health are between 30 and 50%. Below 30% and comfort suffers when it is cold. Above 50% yields mold growth and a clammy feel in cooling season. Sometimes in the winter you can get condensation on cold surfaces (windows for example) and can't reach 30% inside.

Air exchange with outdoors reduces humidity in the winter and, typically, increases it in air conditioning (cooling) season. Sealing up air leaks helps you control that.

An open combustion heater like a fireplace or an unsealed stove draws air into a home to supply the fire. You are probably aware of this because it can cause backdrafts in water heaters which is bad. It also ramps up air introduction from outdoors and dries the air out unless make-up air is supplied right at the device.

Depending on the house and conditions, sometimes I don't use my exhaust fan for showering in the winter to increase indoor humidity.

There are three ways that heat is transferred, conduction, convection and radiation. Heat sources are usually a combination of the three in one way or another. Without going into detail, when you are standing next to an open fireplace, what you feel on the side facing the fireplace is entirely from radiation. Convection requires moving fluid or gas. Most of the heat you feel from any radiator, baseboard or otherwise is via convection in air. Conduction of heat is from direct touching of materials.

it is important to note that the intensity of radiation of any kind, heat, light, x-rays,.... falls off with the square of distance. That means that as you walk away from the stove, doubling your distance decreases the heat you feel by lots more than a factor of 2.

A wood stove gets very hot, so you will feel a lot of radiation. You and other close-by objects will heat up because of it. There is heat transfer from convection as well. Most of what we call radiators are much cooler than that. That means that convection takes over from radiation as a heat transfer mechanism, usually from a broader surface area. The only common household "radiator" that I can think of that may be an exception is a radiant electric heater. These have no fan and tend to feel like you are standing at a fire.

That is why I wrote that you are unlikely to get a fire-side feel from any radiator, baseboard or otherwise, powered by your boiler. The theoretical max temp of your radiators less than 100 C and the practical operating temp is much lower. It pales in comparison to the temp of the surface of a wood stove or an orange-hot electric coil.

Thanks. We will monitor humidity and keep it between 30% and 50% for comfort and mold retardation.

What I take from what you said is that baseboard and radiator will feel pretty much the same.

Putting a chair right next to a larger, upright radiator might give you a tiny fraction more of a fire-side feel than a baseboard radiator.

Honestly, if you want to feel the same kind of warmth of sitting near a fire, a plug-in blanket or "throw" might be your best bet.

Thank you. Considering how difficult it is proving to find a Buderus contractor that has installed their radiators, baseboard would be a lot easier. Our local guy can do that. Appreciate the help.