It is a boast of ours that we are completely indifferent about the heat source that connects to our underfloor heating...well, when it is not one of our heat-pumps, that is. But apart from that if it produces hot water, you can connect it to one of our systems, however we do like to know what that heat source is before we start designing. If for example the heat source has a low flow temperature, we will design the system differently to a system that has a higher flow temperature. To date we can list conventional gas and oil boilers, electric boilers, ground and air source heat pumps, biomass boilers, hybrids and even AGA and Rayburn style range ovens among the appliances we connect with.
For our clients we can offer combined pump/blending valves (the most popular configuration for conventional heat sources), in-line blending valves and bare manifolds if the heat source has sufficient pump capacity. On this renewable energy project our client has fitted a Windhager pellet burning boiler, combined with an evacuated tube solar thermal roof mounted system.
Temperatures from this system therefore will potentially exceed what is regarded as the safe limit for floors, so it was necessary to incorporate a means of tempering the flow from the boiler. As the integral pump within the Windhager pellet boiler was powerful enough for the underfloor heating system, a three port blending valve was supplied. This takes water from the boiler into one port, another port takes water returning from the underfloor heating system (therefore cooler) and the resulting mix is fed to the underfloor circuits.
Quick drying screed
We were contracted to provide the underfloor heating and the screed over the pipes. The depth of screed is typically around 50-60mm. Traditionally a sand/cement screed will be laid to 65-75mm, this operation is quite labour intensive and the results we are sad to say, are only as good as the screeder doing the work. Among the advantages of flowing screed is the speed of application, 300m² to 500m² per day is easily achievable, an area that couldn’t be countenanced by manually applied methods. Access issues are overcome too, as we frequently find when confronted with difficult sites. With hoses extendable up to 100m there aren’t many places we can’t reach.
It was just before we started the project that we learned of a potential problem- the client was moving in within a very short timescale, the screed needed to be dried within an impossibly short time! Fortunately for all concerned, a high performance cement based screed has been developed, our project was among the first in Scotland to receive it. Its exact composition remains a trade secret for the moment, but you can expect to see more of this remarkable material in the future. The screed behaves exactly as we would expect a flowing product to do, but most remarkably it will be ready for tiling within half the time of any other comparable material. The product is batched at the concrete plant, ensuring strict quality control is maintained; further checks on the fluidity of the material are carried out on site prior to discharge.
It all comes together
The project was completed without hitch, the underfloor heating installation was carried out in a neat and tidy fashion (some might argue that out of sight is out of mind- but our fitters would disagree) and screed was timed for the day after the UFH was finished. As the site was in a mid terrace location there was little scope to lose surplus material, a site survey was carried out to confirm the quantities required. The screed team protected the immediate vicinity against concrete splashes, and there was minimal disturbance for the neighbours. We worked closely with the installers of the bio mass system and the electricians and plumber on the project, and the client was kept informed about progress at each stage.