Hi I am renting a house with a Vulcan freeloader 260 outside boiler. We keep finding that we do not have any hot water, we turned the thermostat dial up and this seamed to fix the problem for a few days, how does the boiler actually work ? on demand heating or a thermostat linked to the boiler dial setting. Is there anything I can look at before I have to call a plumber. Regards David Knight

You're looking to install a new hot water boiler or replace your existing boiler. You come across something called a "modulating" boiler. You wonder what on earth that means. I will attempt to explain some of the features of a modulating boiler.

How nice would it be if you could have your boiler make just enough heat to keep your house warm and nothing more? Your thermostat tells your boiler that you need heat in the house. The boiler starts up and heats the water that runs through the pipes to heat your house. The water does not heat up to temperatures that are more than just warm. But you notice that the temperature in your house is staying right where you want it to be.
This boiler is no ordinary boiler. It knows what the temperature is outside and varies your water temperature to make just the heat needed to keep you comfortable. The modulating boiler also runs much more then a normal boiler would but you can see by your gas bill that you are getting great efficiency from this thing.

The feature that makes this wonder so great is that it has the ability to vary the fire that heats the water up and down so that the water temperature stays precisely where the computer brain in the boiler wants it to be. This temperature is figured by measuring the outdoor temperature and changing the water temperature based on that. The colder the weather is outside, the hotter the water is going through your system.

With a system like this you will notice that your heat will run longer and still not cost anymore money. This makes you more comfortable. The modulating boiler will give you just enough heat to keep you warm without wasting much of the heat that a normal boiler would. This type of furnace will give you the most efficient heating possible on any given day.

Before buying a new heating system or replacing your old hot water boiler make sure that you check into a system that will modulate the fire and also vary your heating water temperatures according to the outdoor temperatures. This will save you money and give you a very comfortable heating system.

It is the coldest day of the year and your boiler is chugging along. However you notice that your house is slowly cooling off even though the boiler is running. Then you notice that the boiler is shutting down even though your house is not up to the thermostat temperature setting.

You look into the situation farther and notice that you boiler temperature is below say 180F. What is shutting the boiler off? The device that controls the temperature of your boiler is called an aquastat. This device senses the temperature of the water in your boiler, and then fires the burners to keep the water at the temperature call for by the aquastat.



The other role that this device may play is to keep the boiler from getting too hot and making steam. However for this time we will concentrate on the lower side and the heat of the water. If you have a house that has barely enough baseboard or radiators for that really cold day then you need your water to be very hot or around 200F. This will give the water enough BTU's to carry around the piping to give off to keep your house warm. The downside is that it also makes your boiler less efficient when it needs to heat the water this hot.

So, now you know that if you need more heat you can turn the aquastat up higher to get more heat and turn it lower on the milder days to save energy. Another way to do this is to buy and install a smart control that will do that automatically for you. These are called an outdoor reset control and will vary your boiler temperature according to the outdoor temperature, saving you money and keeping you warm all at the same time.

Now, the one thing you need to know yet. The aquastat is usually a gray box with a screw driver slot in a little wheel that has numbers on it. It is often hidden pretty well and may take some looking to find it. Some of the newer boilers may have a digital one that is in a bigger gray box. Read the instructions to learn to change the temperatures.

Setting your aquastat correctly can save a lot of money and it can be the difference between keeping you warm or not.