Solar
You are here
Controls for an Integrated Forced-Air and Solar Thermal Setup
Control in a batch installation
If your solar thermal system has no storage, the heat gathered by the collectors goes straight to the ducting. When heat is needed, both systems are switched on, so hot solar fluid circulates to the heat exchanger and the furnace blower distributes the heat around the building.
Calculating Flow Rate and Head in Solar Thermal Systems
Choosing the right pump for your solar thermal installation is very important and for that you need to work out the flow rate and head for your chosen setup. Solar loops which are always full only have friction head, whereas drainback systems also have static head.
Integrating Solar Thermal Space Heating with Hydronic Systems
Most residential buildings that have an existing grid-tied heating system use a hydronic rather than a forced-air system. This is generally better for integration with solar thermal installations, though that's a big generalization: there are so many different layouts, implementations and requirements that it is impossible to state whether integration is guaranteed.
How To Choose The Right Solar Thermal Pump - An Example
Let's walk through some example calculations for choosing the correct solar thermal system pump. We'll assume it's for a pressurized antifreeze system, so there's no static head to worry about, and we've installed three collectors, about 100 feet of Type L copper piping, one heat exchanger and a variety of fittings and valves.
1. Collector array flow and head
Controls for an Integrated Hydronic and Solar Thermal Setup
Combining a solar thermal heating system with an existing hydronic installation requires not only plumbing and solar equipment but some extra control gear – both electronic and hydronic – to divert fluid when needed. There are several options available in most cases.
In some situations, you will be able to wire the solar thermal setup into the existing thermostat control system so that the water supply passes through the solar storage tank's exchanger when there's enough heat to do some good.
Pipe Size and Fluid Volume in Solar Thermal Systems
When you're designing your solar thermal installation, you'll need to choose an appropriate pipe size – one which fits the needs of the system and the available installation space and complexity.
Non-Integrated Solar Thermal Heating Systems
Although it is usually preferable to connect your solar thermal space heating installation into a grid-tied system and have the two work together, it's not always possible. Some retrofits simply do not lend themselves to integration, so you will end up with two separate systems. They can still work together, just not to the same extent.
How to Size an Air-Based Solar Thermal Heating System
In air-based systems, it's very important to plan for a collector array of the right size for your needs. It's a difficult calculation for inexperienced installers because you need to strike a balance between the collector output, the amount of thermal mass inside the building and the rate of heat loss from the structure. If you're unfamiliar with calculating thermal mass and heat loss, it's going to be even tougher.
High Mass Solar Thermal Space Heating
One of the oldest known man-made solar thermal space heating systems was built by the Romans, who constructed radiant floors for their bathhouses over 2,000 years ago. The systems heated the bathing water and the buildings by circulating hot air under the floors, then up through multiple chimneys. Today, radiant floors are not only the most comfortable heating system available, but the most economical – especially when tied into solar thermal heat generation!