UFH Heating settings

[Diablo]

All,

 

I have some questions about settings for UFH heating system, which was installed a year ago but was not correctly balanced by the installers as there no boiler in the property at the time.

 

I have 2 Reliance manifolds (7 port and 9 port), currently set at 45deg and pump speed 3.   The pipes are 15mm and set in a 75mm sand and cement screed.    

 

Any advice on optimal settings and how to balance the system?  There was a similar thread recently, but did not wish to highjack it

 

Many thanks,

Rog

[Nickfromwales]

Ok. First off turn the pumps to position 2 / medium. 

Next, do you have temp gauges on the flow and return ? When you say 45oC where is that reading taken from, the blending valve or the temp gauge? 

With that setup I'd have thought you could reduce that to 40oC first and try it.

With regards to balancing, I'd just put everything open fully and wait to see how it performs, adjusting later only if required. 

[Diablo]

11 hours ago, Nickfromwales said:

Ok. First off turn the pumps to position 2 / medium. 

Next, do you have temp gauges on the flow and return ? When you say 45oC where is that reading taken from, the blending valve or the temp gauge? 

With that setup I'd have thought you could reduce that to 40oC first and try it.

With regards to balancing, I'd just put everything open fully and wait to see how it performs, adjusting later only if required. 

Hi Nick,

 

Turned both manifold pumps to position 2.

 

Yes, the 45 deg is the setting on the manifold mixer valves.

 

What effect do pumps speed and mixer temp individually have on performance, e.g. response time?

 

Balancing: Do you mean fully opening each of the 'flow valves' on the manifolds?

 

Thanks again.

[Diablo]

Hi Nick,

 

Just another follow-up: I adjusted my manifold mixer temp to 40oDeg and set the pump to 2.  The one thing I noticed straight off the bat was that the rooms are taking longer to get to temperature.  I assume this means that the boiler is running for longer?     Coincidentally, the weather is also a bit cooler than last week - should these settings be adjusted accordingly, or are they set and forget?

 

Many thanks. 

[le-cerveau]

Nick will answer when he can, but the boiler will not be working as hard, and if it is condensing is more likely to be in condensing mode.  Also you are less likely to overrun on temp and it should be more comfortable.

[Nickfromwales]

24 minutes ago, Diablo said:

Hi Nick,

 

Just another follow-up: I adjusted my manifold mixer temp to 40oDeg and set the pump to 2.  The one thing I noticed straight off the bat was that the rooms are taking longer to get to temperature.  I assume this means that the boiler is running for longer?     Coincidentally, the weather is also a bit cooler than last week - should these settings be adjusted accordingly, or are they set and forget?

 

Many thanks. 

Simple physics. 

If the slab gets to say 35oC surface temperature ( so becomes an emitter of heat ) and the watts per m2 it's chucking out is greater than the heat loss ( fabric AND ventilation ) of the house then the house will warm up.

The flow temp, as set on the manifold TMV, is selected according to how the slab absorbs and dissipates heat, so no two jobs will be identical. 

How much insulation is under your 75mm heated slab?

[Diablo]

We have 180mm of Kay Metzeler Polystyrene insulation and the screed has perimeter insulation all the way around.

[Adsibob]

Thought I’d revive this thread as keen to understand how settings impact performance. In particular, what impact does changing the pump speed have? Mine was set up with all pumps set to position 1 (out of 3). I’ve not had to run the UFH since we moved in in May, but this morning we realised we had left the kitchen window open and so the temperature downstairs has dropped to 18C. UFH has been running for about 50 minutes and it hasn’t warmed the floor covering yet, despite this just being 3mm thick microcement. I guess the heat still needs to get through the 60mm of sand and cement screed (we have 16mm pipes at the bottom of 76mm of screed). Well increasing the speed improve the responsiveness?

[JohnMo]

Our 100mm concrete with UFH pipes in it takes about 6 hours to heat up. Your heating the best part of 80mm.

 

Individual loop flow speed is controlled by the flow meters, increasing the pump speed should have no effect.  Your speed is set to cover the system flow and head requirements.

 

 

 

 

[Adsibob]

11 minutes ago, JohnMo said:

Our 100mm concrete with UFH pipes in it takes about 6 hours to heat up. Your heating the best part of 80mm.

 

Individual loop flow speed is controlled by the flow meters, increasing the pump speed should have no effect.  Your speed is set to cover the system flow and head requirements.

 

 

 

 

In not sure that is quite right. When I increase pump speed from 1 to 2 the flow metres slow an increase in speed from about 2Litres per minute to slightly over 2.5L/min. 

 

[ProDave]

First warm up from cold takes a long time.  I suspect most people used to radiators, turn on the UFH for the first time and think it is not working.

 

Leave it and come back in a few hours.

[JohnMo]

So you are increasing the pump head, which is overcoming the set point of the flow meter.  You should have a defined flow rate for each loop, why would you want to increase that?  Increasing flow will reduce the delta T and increase the mean flow temp which will give an increased floor output. This cause temperature overshooting.

Edited September 25, 2022 by JohnMo
Missed details

[Adsibob]

On 25/09/2022 at 09:03, JohnMo said:

So you are increasing the pump head, which is overcoming the set point of the flow meter.  You should have a defined flow rate for each loop, why would you want to increase that?  Increasing flow will reduce the delta T and increase the mean flow temp which will give an increased floor output. This cause temperature overshooting.

So that means that if you get home to a very cold house (well not that cold, but 16.9C) and you want to boost as quickly as possible by 2C, but you aren’t bothered by overshooting, a temporary higher pump speed is a good idea. Have I understood that correctly? 
generally my heating is very clever, but I haven’t subscribed to Tado’s algorithmic machine learning service (as I’m too cheap and prefer the subscription free service) so plan the adjustments myself using the schedule feature. Got it wrong tonight and SWMBO is complaining the heating is too slow.

[Radian]

8 hours ago, Adsibob said:

I haven’t subscribed to Tado’s algorithmic machine learning service

Ffs. A subscription to get optimised control from the heating control device you've already paid for?

[JohnMo]

9 hours ago, Adsibob said:

So that means that if you get home to a very cold house (well not that cold, but 16.9C) and you want to boost as quickly as possible by 2C, but you aren’t bothered by overshooting, a temporary higher pump speed is a good idea. Have I understood that correctly? 
 

If the flow rate is increasing at each loop, that would suggest DT would come down, so mean flow temp would increase.  The easiest way to get heat in the floor is to just increase flow temp. Instead of making a pump work harder.

[Adsibob]

4 hours ago, Radian said:

Ffs. A subscription to get optimised control from the heating control device you've already paid for?

Indeed. It's the only thing I don't like about their system. You get a lot of functionality for free, but the machine based learning feature is one of the features you have to pay for. £25 a year.

[JohnMo]

I had so called self learning thermostats, but they just couldn't cope this the heat up and cool down times of thick screed and low flow temp.  So next to useless.  House was to hot or way to cold never the correct temp.  So got used as on/off.

[Adsibob]

Going back to @Radian's criticism of Tado (which I share):

6 hours ago, Radian said:

Ffs. A subscription to get optimised control from the heating control device you've already paid for?

It turns out some clever bod has written a Python script to effectively give you Tado's subscription service (called "auto-assist") for free:

https://sascha-brockel.de/en/tado-auto-assist-free/

 

I haven't got the time/brain power to try it, but maybe a project for somebody clever here?

Edited December 9, 2022 by Adsibob

[Radian]

1 hour ago, Adsibob said:

Going back to @Radian's criticism of Tado (which I share):

It turns out some clever bod has written a Python script to effectively give you Tado's subscription service (called "auto-assist") for free:

https://sascha-brockel.de/en/tado-auto-assist-free/

 

I haven't got the time/brain power to try it, but maybe a project for somebody clever here?

That covers geofencing and window open functionality. I'm not seeing anything to get really excited about. You surely must have remote control of temperature on the free app?

[Adsibob]

7 hours ago, Radian said:

That covers geofencing and window open functionality. I'm not seeing anything to get really excited about. You surely must have remote control of temperature on the free app?

You are right. It doesn’t provide the machine based learning.

 The free app is generally very comprehensive. You can:

- create lots of schedules and easily copy schedules across from one thermostat to another or from one day or day pattern to another

- control temperature to the nearest tenth of a degree, both on the schedule and in real time

- you can also see how each thermostat behaves when you are home or away

- track months worth of temperature and humidity data on each thermostat - and it draws nice graphs for you which in addition to displaying humidity and temperature, also display the local weather and whether or not you had your hot water and/or heating on at the time, so you can see if you can spot any correlation between those factors.