How to control floorheating

[vanisher]

At our house we have the following situatiion:

Remeha Calenta
Rehema iSense
Floorheating downstairs and in the bathroom
Normal radiators in the rest of the house
In the livingroom we have a pelletstove (hot air).

I'm looking for a solution to steer the Remeha when we use the pelletstove.

Currently the situation is that if we use the pelletstove, the Remeha is nog heating because the iSense is in the living. So we have a cold floor downstairs and on the first floor there is no heating as well.

The iSense has an stove (kachel) funtion but it's not very clear how it works. As far as i know the Remeha keeps behaving like it was the moment you set the stove function.

What i would like is to steer the Remeha with domotica and use hydronic valves on the floorheating system.

Like: If pelletstove is on, close floorheating groups livingroom.

Currently i'm setting up a jeenode to measure the outgoing and incoming temperature on the floor heating groups (7).

But what do i need as hydronic valves and what do i need to steer those valves which can also be connected to homeseer.

[enix]

Hi vanisher,

I'm looking for something simular, have you ever figured out a setup that fixes this issue?

thanks,
Ernst

[Post-IT]

As far as the floorheating goes, I've used an automated pumpswitch in combination with a thermovalve to control the whole floorheating block at once. Shutting all zone valves while leaving the pump running is really not good for the pump.

The pumpswitch: http://www.tercal-shop.nl/product_info. ... e-antistop

It measures the incoming temperature and switches on/off on demand. It also switches the pump on/off every week or so when not using regularly to prevent pipe blockage or pump problems. So this device is simple, cheap and does most of the thinking on it's own. And it also saves on the energy bill. All that is left is controlling the whole unit (inflow) and in necessary individual zones.
When the heat is turned off the pump will go on for some period which results in a more gradual temperature change and more comfort.

I've put a 22mm thermovalve set just before the block and pumpswitch sensor:
http://www.heatnet-vloerverwarming.nl/s ... ensor.html

This set has a 230V thermovalve so it is steerable using any kind of on/off switch such as a plugwise circle. In my situation I have a thermostat device which sends on/off commands to the switch for this thermovalve.

I've also used 230V thermovalves on some of the zones (not all) which I control as an add-on. For example, I would normally regulate the livingroom but only sometimes the study next to it. So the study will only be turned on when the livingroom is on. Using movement I turn on the study zone thermovalve(s). However you might be able to reverse this by putting a temperature sensor next to the stove which will close the livingroom zone when sensing over 50C at the stove.
Depending on the floorheating block you have you might need a different type of thermovalve. Robot floorheating for example need a 30x1,5 with an extra long travel, a regular 30x1,5 thermovalve would not open the zone completely. So take care in selecting the correct thermovalves for the zones.

On the thermostat part, if you want to regulate different rooms in a different way you will need a thermostat device for each room (actual or virtual) including the temperature sensors for those rooms. As I've stopped using HS several years ago I don't know if you might be able to create a good thermostat function in HS.
When choosing software/hardware to create supplemental thermostat you might want to think about what type of regulation you would like: 2-point (classic) or proportional integral (PI). When floorheating is the main heatingsource a regular 2-point thermostat is sometime not comfortable as it stops to heat 0,5C above setpoint and starts again 0,5C under setpoint, which results in longer periods of uncomfortable temperatures (highs and lows).

Hope this helps a bit.

[enix]

Hi Post-IT,

this helps a lot! Thanks for your detailed reply and links.

I have a Robot floot heater with a Grundfos Alpha2 pump. The Robot manuals are a bit spars in terms of information density but it states that a separate pumpswitch ('pompschakelaar') is not needed (1). I'll contact the guy who installed my system to ask if he knows what happens if I shut off the water supply to this system using the electric valve you've mentioned.

Again, thanks for helping me get started.

cheers


1: Robot manual; http://www.robot-vloerverwarming.nl/dow ... 20pomp.pdf

[Post-IT]

Shutting the inflow for the whole block is no problem as the pump will cycle the water in the system continuously until it has reached a certain low-temperature (all heat in the water has been absorbed by the floor), inflow will only "add" warm water to the system.

It's a problem when you shut all zones. This will result in the pump trying to pump maybe even less the 1liter continuously. You will hear the pump noise change when all zones are closed showing it has a hard time doing it's (useless) job. However I don't know how the Alpha2 reacts in this situation. I also thought about buying two new Alpha2 pumps but buying two pumpswitches was much cheaper. In your case you would not need a pumpswitch as the Alpha2 function is similar (pump only on demand). I called Robot about this a few months ago and they advised not to close all zone valves. This is why I decided to put a main valve on the inflow. The plus in this situation is that the warm water in the system will be pumped through the system for as long as it has heat energy, so you don't throw away heat energy and secondly the heat will not stop abruptly but gradually bringing more comfort in the ambient room temperature.

In case you want to buy zone valves, you will need the Robot NC 601520 valves (230V version), available at Technische Unie. I only use 230V valves to save energy. When I used the 24V version in the past I had a transformer running 24/7 even if I didn't use the valves. So this saves me about €70 over the year.

[enix]

It makes sense that the pump needs some room to do it's job and that tightening all zones well cause pump friction.

For now I'm not planning to close down individual zones. Partly because we have an open kitchen that is attached to the living room making it basically one big area and partly due to lack of actual experience on how the system behaves. It's so new that the floor is still drying

Again, thanks for the detailed information and insights on how these systems operate.

[Digit]

I shut down the floor heating pump when room temp > room setpoint.

[enix]

Hi Robert,

that's the easy way to achieve the same goal

[Post-IT]

That works also. However the fluctuations are higher in that case, resulting in less comfort because the deviations from the setpoint are larger most of the time. Depending on the situation you could partially compensate with thermostat settings.

And of course the comfort is largely dependent on the room/building. In my case a band of 0,5C is not acceptable comfort wise.

[Digit]

However the fluctuations are higher in that case

That's a bit too short through the corner
It depends on how you do it. The way I do it, fluctuations are not noticable (higher).
I even dare to say they are lower than they were before.

I've got 2 time triggered events:
1. every hh:00 and hh:30 it checks if room temp < room setpoint for > 5 minutes. If so, the pump is switched on (if not already on).
2. every hh:15 and hh:45 it checks if room temp > room setpoint for > 5 minutes. If so, the pump is switched off (if not already off).

The reason for using time as trigger (and the 5 minutes) is to reduce the influence of noise on the room temp sensor which would otherwise cause much more switching. So let's say room setpoint is 20.5 degrees C; 20.4 is less than 20.5 so the pump will be on. But 20.6 is greater than the room setpoint so the pump is off.

Nobody says you have to use -0.5/+0.5 degrees to determine when to switch...
I've been doing this since February and I like it.
Here some data; to show how often the pump has been switched during the last days:

Code: Select all

2013-04-02 09:15	Floor pump off
2013-04-02 02:30	Floor pump on
2013-04-01 09:15	Floor pump off
2013-03-31 23:30	Floor pump on
2013-03-31 09:15	Floor pump off
2013-03-30 20:00	Floor pump on
2013-03-30 18:45	Floor pump off
2013-03-30 18:30	Floor pump on
2013-03-30 08:45	Floor pump off
2013-03-30 01:30	Floor pump on
2013-03-30 01:15	Floor pump off
2013-03-30 01:00	Floor pump on
2013-03-29 02:15	Floor pump off
2013-03-29 00:00	Floor pump on
2013-03-28 21:45	Floor pump off
2013-03-28 19:00	Floor pump on
2013-03-28 09:15	Floor pump off
2013-03-28 00:00	Floor pump on
2013-03-27 08:45	Floor pump off
2013-03-27 00:30	Floor pump on
2013-03-26 08:45	Floor pump off
2013-03-25 23:30	Floor pump on
2013-03-25 08:45	Floor pump off
2013-03-25 01:30	Floor pump on
2013-03-24 03:15	Floor pump off
2013-03-24 02:30	Floor pump on
2013-03-23 19:15	Floor pump off
2013-03-23 17:30	Floor pump on
2013-03-23 09:45	Floor pump off
2013-03-22 18:30	Floor pump on
2013-03-22 07:45	Floor pump off
2013-03-21 21:00	Floor pump on
2013-03-21 20:45	Floor pump off
2013-03-21 20:30	Floor pump on
2013-03-21 19:45	Floor pump off
2013-03-21 19:00	Floor pump on
2013-03-21 08:15	Floor pump off
2013-03-20 20:30	Floor pump on
2013-03-20 12:45	Floor pump off

BTW, this is just a small step of something 'bigger' I'm working on, which will probably be continued next winter..

[Post-IT]

That's why I said you can compensate using thermostat settings for as far as your thermostat/system allows it. And of course you might have a good combination of thermal lag in your house which in combination with your specific heating makes it easy to do it this way. However that might not always be the case. I'm not so lucky for example.

0,5C is not an unusual number for a regular thermostat. Looking at the attached image, all the red and blue is where the ambient temp does not match setpoint, could also be said to be the uncomfortable zones.

2-point graph

Screenshot 2013-04-02 at 15.47.15 .png (31.26 KiB) Viewed 13862 times

By adjusting the upper limit and lower limit you can decrease these "uncomfortable" zones, but it might increase on/off cycles (which in my opinion is not a problem).

If you let the pump run for a while longer without adding more heat to the system the energy will be dispersed more evenly as you can see in this graph.

2-point with pumpswitch

Screenshot 2013-04-02 at 16.00.55 .png (57.49 KiB) Viewed 13862 times

It is not wrong, but just a different approach. You could compare it to your car: you can cut power to the fullpump and it will slow down, but I prefer to use the gaspedal and do it gradually. Depending on the luxury of the car and the skills of the driver the passengers will or will not notice the difference.

[Bastiaan]

I am also using floor heating and radiators in the house. Boiler is controlled by outside weather temp and adjusting water temp automatically. If there is a demand it will run the pump (modulating system). I control my radiators with the MAX! valves and control the floor heating pump with a Zwave thermostat controlled from Homeseer.
More or less the same setup as Robert and it is working fine for years.
I might be able to save a bit more if I start switching the boiler off from HS but for now it seems not worth the risk of frozen tubes if HS crashed.
The overshoot mentioned above is hardly there in my case. When I was using a (self learning) Honeywell thermostat is was slightly better but now with my relative simple system it has been fine too. I am using a floorheating system of aluminium sheets and copper tubes on foam, as used in ships to save weight on my 100 year old house / first floor.

[Commodore White]

Wish I'd read this post earlier when I was trying to decide how to heat my new house. Its been very valuable reading. My design is uf heating by nu-heat downstairs and radiators upstairs - fairly traditional by all accounts. Hot water top up is by solar panels from Grant.

I have a raspberry pi at present running domoticz and Domotiga whilst I valuate ease of use. I have lots of homeasy sockets and dimmers so I've bought a rfxcom unit - it works well. I'm going to get some 1-wire thermometers to measure solar temperatures though I'm not sure what I'll do with the results. I was hoping to control the nu-heat stuff from the Domotiga but I don't know how easy this will be. Will contact nu-heat this week to see what help they can provide.

I was hoping to incorporate fire and intrusion detection but am concerned about having too many eggs in one basket.

Thanks again.