Help me understand our central heating!

marks87

We had a brand new central heating system installed at the start of the week, and it's the first time we've had CH (old house + lack of funds =ed costly electric ).

Anyway, the plumber explained the basics of how the system works and how you control the temperature. But we're still not entirely sure how to get the optimal settings for the whole house, so I was hoping someone on here could explain in reasonably simple terms!

We have radiators throughout the house with TRVs, except in the living room where the thermostat is - I believe this is normal, yes? We can then set or programme a temperature for the boiler to then kick in and start heating the house. The TRVs can then be used to control the temperature in the other rooms. That's straightforward enough.

What's confusing is is what happens if, say, we have visitors and the living room gets warm enough to cut the boiler based on the temperature detected by the thermostat? Does that mean the rest of the house will be cold because the living room is too hot? If so, what's the solution? Or have I completely misunderstood.

My gut feeling is that the system must work to heat the whole house somehow, including hotter and colder rooms - otherwise, nobody would ever want it. But being CH n00bs, we don't quite yet understand it!

The thermostat we have is a Worcester Wave, if that makes a difference to how things work.

CashStrapped

You are nearly there....but not quite.

Welcome to the world of on demand heating!

These are the controls you are most likely to find on your system and how they work.

1) Controls on the Boiler itself. These controls will determine the temperature the water is heated to. On a combi, usually one for heating, the other for hot water to taps. In terms of Central Heating, the temperature of the hot water running through the radiators affects how quickly a room or rooms will heat up. (see combi boilers/condensing boilers side note below)

2) Whole house thermostat. This does not control the water temperature or anything like that. It simply tells the boiler to turn off once the room temperature (wherever it is situated) has been reached.

So to give an example of those two working together. If you have the boiler water temp on very high. The radiators may get red hot and warm the room up very quickly. At which point the thermostat will cut of the boiler when the room reaches the required temperature.

3) TRV valves. These again monitor the temperature of the room. Depending on the setting on the TRV, these will cut off the supply to the radiator while the room is at the desired temperature. It does not stop the boiler from running, but allows a room to be bypassed to give the boiler an easier time heating other areas. If the room cools too much (depending on the setting) the supply to the radiator will be restored.

Thermostat side note: You are correct in that if the whole house thermostat is put in a warm room then the heating to the rest of the house may be shut off. This is because the boiler thinks the whole house is at that temperature. A thermostat should ideally be placed in an area in the house which gives a decent average temperature (this is why they were usually placed in hallways, but away from the front door). Another solution to this is to get a decent wireless thermostat (honeywell are a good brand). This will allow you to place the thermostat anywhere in the house. You can then find a good place for it.

Combi boilers side note: Modern combi (or any modern condensing boiler) boilers work more efficiently when the system is used at the lowest temperature (controls on the boiler) possible to keep the house warm. Therefore there is an incentive to run the central heating system at a warm temperature for longer rather than very hot for a short period(s). This is because it allows the condensing part of the boiler to recover more waste heat. This will improve boiler efficiency. This only happens at a lower temperature.

I hope that helps!

marks87

OK, I think I've got that. Thanks.

The plumber fitted the thermostat to the living room wall. The living room is usually average, but can get warm if we have visitors.

Would I be right in thinking that it's best to leave the living room door open as much as possible? Obviously we've been in the habit of having it tight shut to keep the heat in, but with central heating I guess the aim is to let the heat spread as much as possible to heat the house as opposed to individual rooms.

Is it also the case that we need to give the system time to "bed in", maybe once the (really) cold weather starts? We also have triple glazing and insulation so I'm thinking that once the system properly house once, the radiators will then just simmer along nicely to maintain the heat.

CashStrapped

I do not see why a system would have to "bed in" in any way.

In a modern property a wireless thermostat would be the best solution if you are having issues with maintaining a consistent temperature for the thermostat.

If leaving the door open gives a more consistent temperature then that is fine but I can imagine it getting a bit annoying.

It is all about temperature consistency for a thermostat to work best.

There is no method behind heating the house well to get it warm once, then letting the radiators simmer.

All houses will lose heat in relation to their individual insulation specification. This will be at a specifics rate of heat loss. So, you will in time get used to how quickly your house loses heat, what is comfortable for you and so on. You can then set the boiler controls and timers accordingly. As per above, the lower the radiator temperature that you can achieve this with, the more efficient your boiler may run.

Basically, all heating is, is replacing warm air faster then your property loses it.


In addition, now you have central heating and a nice insulated house. Never dry clothes on your radiators. If you have a tumble dryer, use that or a line. Otherwise you may get massive damp problems. This would be more apparent in a well insulated house as all the evaporated water from your clothes is trapped inside the house. It will eventually condensate on cold spots on walls and eventually cause damp and mould. Ensure you have good ventilation in the kitchen and bathrooms. People do not realise, the more you insulate the more you need good, controlled, ventilation.

Cardew

marks87 wrote: »

What's confusing is is what happens if, say, we have visitors and the living room gets warm enough to cut the boiler based on the temperature detected by the thermostat? Does that mean the rest of the house will be cold because the living room is too hot? If so, what's the solution? Or have I completely misunderstood.

My gut feeling is that the system must work to heat the whole house somehow, including hotter and colder rooms - otherwise, nobody would ever want it. But being CH n00bs, we don't quite yet understand it!

You haven't misunderstood. With a fixed room thermostat it is often impossible to heat up other rooms because that room(the living room in your case) is too hot.

A partial solution is to buy a wireless thermostat that you can move from room to room, but if you move it to, say, the hallway other rooms will heat up, but in your case the living room will continue to heat up even more as you don't have a TRV on the radiator in the living room.

There is no ideal situation, it is all a compromise.

reeac

My experience is that there is a fair amount of diffusion of heat throughout a building thus spreading the heat around even if a radiator is off. We live in a bungalow and so have no convection from downstairs to upstairs but our bedroom which we practically never heat (through preference not for economy) never gets really cold ....maybe 12-14 C when the hall thermostat is at 20C. Have you actually found from experience that you get this "visitor effect" in just a few hours?

teddysmum

We have a wireless thermostat that I specifically asked to be left portable and we choose to keep it in the living room as that is the room most used. The radiator valves in other rooms are appropriately turned down, with the bathroom one being turned up when anyone intends to have a bath.


You will know that the thermostat is set with a choice of temperatures over a number of time periods (setting overnight much lower), but it is possible to override a set temperature just for the duration of the current period. (eg for a 9am to noon setting, you could drop the temperature by 2 degrees , but it will revert to the permanent setting after noon, when you can again alter the setting, if you wish.)

bsod

Your thermostat is in the wrong place.

cheapest solution is to up the temp of the thermostat, and move a trv from a cold room (eg hall, bathroom) to the living room, or adjust the valve yourself if too hot.

Also, all rooms don't need to be the same temperature, so you may want your living room at a higher temperature than the bedrooms anyway.

Cardew

teddysmum wrote: »

We have a wireless thermostat that I specifically asked to be left portable and we choose to keep it in the living room as that is the room most used. The radiator valves in other rooms are appropriately turned down, with the bathroom one being turned up when anyone intends to have a bath.


You will know that the thermostat is set with a choice of temperatures over a number of time periods (setting overnight much lower), but it is possible to override a set temperature just for the duration of the current period. (eg for a 9am to noon setting, you could drop the temperature by 2 degrees , but it will revert to the permanent setting after noon, when you can again alter the setting, if you wish.)

But the dilemma facing the OP(and others) is that when his living room is up the temperature he requires, there is no heating to the rest of the house because the heating is switched off by the room thermostat..

Getting a wireless thermostat and moving it to a cooler part of the house will start up the heating, but his living room will then get even hotter because he can't turn off the radiator.

In your case where you 'chose to leave the wireless stat in the living room'
you will face exactly the same dilemma in heating your bathroom when the living room is at the required temperature.

Cardew

bsod wrote: »

Your thermostat is in the wrong place.

cheapest solution is to up the temp of the thermostat, and move a trv from a cold room (eg hall, bathroom) to the living room, or adjust the valve yourself if too hot.

I tend to agree, but it is now mandatory in new systems for the radiator in the room with the thermostat to have no TRV.

lstar337

Cardew wrote: »

I tend to agree, but it is now mandatory in new systems for the radiator in the room with the thermostat to have no TRV.

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 thermostat. 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.