In the latest episode, "Garage Fire, Furnace Failure", Uselding and Meehan visit Chris and Sally and their three teenage boys who had to flee their home after their propane heater in the garage caught fire and started a blaze.

As they cleaned up the damage, Uselding and Meehan pointed out some basic safety measures that can help prevent fires and also keep a home's heating system in good condition. Here's what we learned this week from the sisters who saved their lives

"I was just about to start cleaning out the garage when I pressed the ignition on the propane heater and it went up in flames right in front of me," Chris said, explaining what started the fire.

Chris and Sally have been using propane heaters in their garage for years and the sisters say it's OK, as long as people take some precautions.

"There are a few safety tips you have to keep in mind when using a propane heater," Meehan said." The first is to make sure you have a well-ventilated space.

Second, she continues, "You need to make sure there are no debris or objects near the heater that could catch fire quickly."

Uselding is quick to add, "Chris did both of those things, so he did everything absolutely right. It was just a bad accident."

However, when the garage was rebuilt, they decided they had had enough of propane and installed an electric heater instead. Once bitten, twice shy!

The whole family was at home when the fire broke out. The two oldest boys were downstairs with Sally and when she realised the fire was burning, she shouted, "It's on fire! Get out of the house!"

"The family had an escape plan, which was good news for us," Uselding said." You don't think these situations will happen in your home, but to be able to plan and act when they do is quite remarkable."

Chris and Sally's kitchen cabinets look OK, but after an in-depth inspection they'll have to go.

"The wood may be saveable, but the melamine in there isn't," Meehan explains, as she scrapes up a finger full of soot.

"It's the same with your countertop," adds Utherding." It's a plastic laminate, but underneath that is particle board. We can't seal it or clean it or anything, so it leaches that smell right into it."

Insurance only pays for the quality you start with, so the family decided to put in an extra $10,000 of their own money to upgrade and make the kitchen look fantastic.

In addition to renovating Sally and Chris's house, Useltine and Meehan drove to Edina, Minnesota, an area known for its top-notch schools that attract students from all over the United States, and then provided accommodation by the ABC (A Better Chance) Foundation.

"The ABC Foundation provides accommodation for scholars from all over the United States so they can get a good education," explains Meehan.

The sisters do volunteer work for the organisation, which has asked them to help repair a furnace that has stopped working. As a result, the basement where the children were studying was frozen. One look around the room and they immediately know why the furnace may have overworked and quit: the exterior walls of the house are made of concrete blocks and it is easy to see that there is no insulation there at all.

"If we didn't do any insulation on this outer wall, we wouldn't be able to keep any heat in," Uselding says.

The answer was to build a two-by-four wall of insulation inside the concrete block wall.

An expert was called in to find out why the furnace had stopped working. The first thing he did was to check the furnace's filter. When he pulled it out, he announced, "The culprit is right here!"

Because the outer walls were not insulated, the furnace kept running and the filter got dirty faster. The furnace has a safety switch that shuts off when the filter is full and the heater can't get air in.

A new furnace filter costs only $25, which is much cheaper than a technician coming to your home - and much cheaper than trying to heat an uninsulated basement in Minnesota.

Experts recommend checking your filter once a month during the winter. It can save electricity and hundreds of dollars in heating costs.

Once the insulated walls were added, Uselding and Meehan picked up where they left off and renovated the entire basement to make it a haven for learning. The students can now enjoy the warmth and comfort.

Meanwhile, Sally and Chris are thrilled with their newly renovated home.

"It was horrible to come back to the house in the days after the fire," said Chris.

"For me, this process has given us a chance to be excited about coming home," said Sally.