Help me understand our central heating!
Comments
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I think that is the main technical reason (what you suggested) Istarr337. That one rad should not have a TRV so there is always some guaranteed flow.
But I also think that is considered inadvisable (maybe just guidance) to put a TRV in the same room as the stat because, in an enclosed space, they may interfere with each others operation.
The TRV may cut off the radiator (if set at a different temp), so the room stat may think that the room is not up to temp and keep the heating on. The rest of the house would then get very hot. Obviously that is just one permutation of what could happen.
Your hallway may be open enough and have enough air movement to avoid this happening.0 -
When did this come in Cardew?
I only ask because our house (built 2014) has a TRV on the rad in the hall, the same room as the TRV. I always thought it was odd, but it doesn't bother me because I leave it on full anyway.
My only thought was that maybe our boiler doesn't require at least one rad to be always open, maybe it has the ability to divert through an internal loop or something.
I assume you mean 'same room as the thermostat??
I have seen the regulation about TRVs on loads of websites e.g.
http://www.ukplumbersforums.co.uk/central-heating-forum/46092-trv-valves-room-thermostat-compulsory-new.html
I have TRVs on every radiator. This enables me to control the temperature in every room in the house with a TRV. However if 2 or 3 rooms are in use, it means moving the wireless thermostat from room to room if one room is up to the required temperature.0 -
Yeah, sorry.
Same here. I just wondered if there was something non-standard about my installation.
The reason for having one radiator without a TRV is to still have a flow when all radiators are off(TRVs up to temp)
You, like myself, will have an automatic bypass valve.
http://www.honeywelluk.com/products/Valves/Bypass-Valves/DU146-Automatic-Bypass-Valve/The DU146 saves energy by only allowing flow through the bypass when needed i.e. when flow through the system is reduced when zone valves or radiator thermostats are closing. The use of an ABV is recommended by the UK government as Best Practice in the CHeSS (Central Heating System Specifications) guide to central heating systems.0 -
Generally if you've got a TRV in every room the system should have a bypass valve which maintains flow through the boiler until it shuts down.
Ideally you should leave the TRV fully open when there's one in the same room as the main system thermostat as you'll get the situation as outlined by Cashstrapped above.Never under estimate the power of stupid people in large numbers0 -
We have trv's on all our radiators and use a portable wireless thermostat to control the temperature of the room/s we are using. In the room that has the thermostat the trv is turned up to max and in other rooms the trv is either off or set at the required temperature. This works for us and saves us a fortune by not heating the rooms we are not in!0
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The art of radiator central heating is a delicate balancing act.
With "property developers" slicing up houses willy nilly, it takes even more judgement than when you had a simple four bed semi to configure.
The TRV is not telepathic, all it does is detect the room temperature and shuts off the flow. What you can do is to adjust the other valve on the radiator, called the lock shield valve.
You can tighten the lock shield valve in the living room, so that the flow is low, i.e. less heat gets to the living room relative to the other rooms. In extremis, you simply close the radiator in the living room, so it is always the coldest room in the house.
You should always leave a radiator freely flowing, so the circulation pump won't overheat, and eventually die. People say there is auto-shutdown, but it's just good practice not to block the flow totally.0 -
Thanks for all the replies and insights.
It's been slightly colder the past couple of days and we have noticed that when the boiler program kicks in for "high" temperatures (7am in the morning and 5pm in the evening), the heat generated is well retained by the rooms. So even if the radiators aren't "on" because the living room is hot enough, the rooms are still plenty warm.
I've been looking at the different bits of the Wave app and I was wondering what weather compensation does? The installer mentioned it briefly but didn't go into real detail. Only that this system doesn't have its own external sensor but instead uses several online weather sources to determine the temperature.
When I look at the settings, there's various things - End and Start point curves, max and min flow temperature and, the one I'm intrigued by, "room influence" - which I can set from "None" through "Low...", "Medium..." and "High temperature system". I'm assuming this is something to do with how much the reading from the thermostat is considered when determining whether to heat? And it's therefore possible to heat the house without over-reliance on the living room thermostat?
Is using weather compensation recommended? And if so, can anyone shed any light on how it works? I switched it on to see what happened and I noticed the boiler fired up and the radiators all heated up (it's 6C out there just now). It now keeps coming on and off more frequently than before.0 -
All boilers these days are condensing boilers. It is important to understand that they operate most efficiently when they are in condensing mode. There are thousands of websites that explain the principle of a condensing boiler but this is sufficient:One of the hot gases produced in the combustion process is water vapour (steam), which arises from burning the hydrogen content of the fuel. A condensing boiler extracts additional heat from the waste gases by condensing this water vapour to liquid water, thus recovering its latent heat.
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An increase of efficiency can be as much as 10-12%.The effectiveness of this condensing process varies, it depends upon the temperature of the water returning to the boiler, but for the same conditions, it is always at least as efficient as a non-condensing boiler.
To get the water temperature returning to the boiler as low as possible, the output temperature should be as low as possible; and that essentially is the purpose of weather compensation. It senses the outside ambient temperature and adjusts the boiler water temperature.Boilers can only condense when the flue gases within the boiler are at their ‘dew point’ of 57°C. So to ensure continuous condensing operation the heat exchange surfaces and therefore the return water must be at this temperature.
There are two ways to achieve this. Design the heating system so that its return temperature is low (underfloor systems for example). Alternatively control the boiler flow temperature so that it runs as low as possible for the longest time. Letting the boiler automatically ‘ float’ in line with weather demand is the proven approach. Does it matter if you run the boiler at low temperatures? Not for most of the winter. In an average British winter only perhaps 30 days out of 200 are anywhere near the temperature (0°C) that the system was designed to provide for.
An average winter temperature is around 10°C, so it pays to keep the boiler running at a low figure as long as possible.
Weather compensation can do this automatically.
Weather Compensation Explained!
Weather compensation controls enable a condensing boiler to work at its optimum efficiency. The controls allow the boiler to vary its operating flow temperature automatically, day by day to suit the weather outside and the temperatures inside the house.
Weather compensation works with a sensor outside and another in the boiler communicating with each other, all the time and varying the boiler's water flow temperature accordingly, rather than the boiler turning on and off which wastes energy.
The aim is to keep the temperature as low as possible and so the boiler condenses for virtually all of its operating period.
Fitting weather compensation can increase the efficiency gain of your boiler by 10% and this can all be achieved from as little as £100 extra.!
Viessmann boilers come with the connections and control on the boiler to make weather compensation a "plug and play" option.
Click to view the Vitotronic 200 control with weather compensation0 -
I've been looking at the different bits of the Wave app and I was wondering what weather compensation does?
My Glowworm just gives me Profile modes 1,2,3 and maybe 4 to choose from.
About twenty years ago, I was with a German, trying to figure out the boiler controller for his apartment building, about four flats are supplied from the basement boiler. It was a PID ( Proportional Integral Differential ) controller! The Differential is really wild! It reacts exponentially to RAPID change in external temperature.
Well, the neighbours can open the windows if it gets boiling hot.
this system doesn't have its own external sensor but instead uses several online weather sources to determine the temperature.
That is so clever: so is it actually connected to the internet?
Or does it have its own GSM connection?
This is what an outdoor sensor looks like:
https://www.plumbnation.co.uk/search.php?search=outdoor+sensor
Supposed to be out of sunlight to avoid false readings.
I bought my own, then the Gas Safe engineer wired it wrong anyway, so the boiler never enabled weather compensation, until I ended up redesigning the whole thing. He also fried the first Programmer by wiring it like a three wire thermostat into 230v AC.0
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