Central Heating Integration

charris cy

Active Member
We have been avoiding so far to integrate central heating systems.

The system we have been asked to integrate is an underfloor water based one with zone thermostats in each room. At the beginning, I though this is easy since the thermostats should be dry contacts and we can replace them with communicating Aprilaire (same as AMX or Crestron) ones. But even if this is the case we must find a way to control the main heating controller and this might not be easy. This controller it usually on a timer and is switched on at different times when needed. It also handles the hot water of the house. Also it seems this controller works based on the outdoor temperature, indoor temperature, boiler temperature and the pipes temperature. Reading more on the subject I found out that these systems are very slow, can be quite complicated and very difficult to integrate.

This is a post from an experienced US integrator discussing this in another forum
:
"Control of convecting heating sources can be simple or very hard. Many systems rely on a circulating pump and this is in essence a digital system--the pump is either on or off-- that any thermostat can control. Others rely on a manifold that has many positions--much like the accelerator in your car and these are almost impossible to control as the thermostats need to behave as analog devices moving the manifold more or less open for more or less water flow. The usual suspects who make automatable thermostats have yet to come out with units designed to control these systems and the thermostats that do control them cannot be automated.

As a side light, there are 2 ways of sensing temperature of radiant floor heat. One is to use a slab sensor and the other to use a sensor, built in to the thermostat or a stand alone sensor, at normal height, say 48-58 inches AFF. Radiant heat is in many respects the most comfortable but it is a slow responding system. It takes time for the heat in the floor to radiate into the room. Slab sensors are great at protecting the system or the floor material but less good at predicting the proper temperature where a person would be comfortable. A sensor mounted normally is better at determining and maintaining a temperature where one is comfortable but will not protect against the system over heating the floor and damaging the floor material"

What worries me are those manifolds and those 3 or 4 way valves that I do not understand how they work.

Please do not advice to leave this on the HVAC contractor and to ask for an interface because this does not work in my country. If I am going to do this I have to know everything about it and be on top of this.

I have to find a solution for this. This is a 2000sq.m. home and they are going for a 300k+ AMX system. It would be a shame to leave the heating system out.
 
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neilball

Well-known Member
Where abouts are you based? There are a few rock-solid choices for HVAC integration in the UK from specialist controls companies who only work in the residential sector and understand the contractual requirements/expectations of this market sector. The two main players both have drivers for AMX & Crestron and offer full design-advice, supply and commissioning of the control system. If it needs "proper" control of the main plant (which can easily become as complicated as commercial/industrial installs on high-end houses) with full integration then do make sure you look at these residential specialists rather than getting sucked into a commercial BMS-type packages which will work but are not suited to residential installs IMO - too complicated for the end-user to manage and bespoke programming can make it difficult to maintain long term unless you buy maintenance support from the original supplier.

I currently run the Scotland office for one of these companies and spent many years working for the other so know both quite well. I also spent many more years working in the commercial BMS controls industry so know that sector pretty well too ;)

I don't want to break any forum rules posting here directly so feel free to drop me a PM if you want any more details.
 

charris cy

Active Member
Thanks for all the answers so far. Heating is the last thing left to find a solution in our big integration projects. The problem is that the US systems are so different to ours. AMX has just withdraw their latest Tstat from Europe because it is not suitable with our systems.

We have managed to find excellent 2 way solutions for Air Condtion Systems and the Security Systems integration which are also quite difficult.

Please help to educate us more on central heating systems and how we can integrate this very difficult subsystem.
 

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