Any damage to boiler on while all radiators off?

[AlanB1976]

Hey all

Just hoping someone can advise, if the central heating is on but all radiators are closed, will that…
1 - Damage the boiler in any way?
2 - Cost much?

To give some context, I want to get the independent smart radiator controls (the ones where each radiator operates independently depending on their own schedule and room temperature). The problem I see is firstly I would have to have the heating on the entire time (unless I know all heating will be off – e.g. middle of night) so that when one of the independent radiator valves open, there is heated water to use. I don’t know much about central heating but I’m assuming that if all radiators are off, the boiler may just need to keep the water that is present in its system at the desired temperature, which wouldn’t cost much. I just worry if that would damage the pump. This would also be pointless if it still costs a fair bit running it like that.
There are total systems like the new TADO one, but to would cost me about £450 to do my house, whereas I can buy separate independent controls which would only set me back £210.

Thanks for any help
Alan

 

[motorbiking]

If the rads are closed but central heating pump/valve still on your system will still heat all the pipes in your house. depending on how well insulated they are will determine how much energy is being wasted under floor and in ceiling. The boilers will also reduce output if the return water is still hot as it won't have to burn to bring the return water back to temperature.

Personally, I'd want a smart controller for the boiler too and have this on a schedule to suit.

are you planning on having different rooms at different temperatures at different times of the day ?

 

[Agile]

A "proper" control system like the Evohome will bring the boiler on as required.

Running the boiler constantly with all TRVs closed can potentially damage the boiler, wastes energy and does not comply with the Building Regulations.

You don't tell us your boiler make so I cannot advise how it might be affected.

Running the boiler all year with the TRVs closed would probably cost about £200-£300 in fuel costs. Very silly!

Tony

 

[AlanB1976]

Thanks for the replies. It wouldn't be run 24/7 like that but the boiler would need to be on over the majority of needed heating time. The boiler would still have a standard scheduled controller but there would be times when all radiators are off and boiler still on. If there is a chance of damage I'd rather not tempt it. I can't remember the model of boiler off hand so will try dig that out. The idea was even if this didn't produce savings, it would allow more flexibility in the rooms. For example, I hate getting out of a shower into a cold bathroom, so I probably want that sitting at least 23 degrees, while in the other areas I want it closer to 20. Then the baby's room will be 18 degrees as for some weird reason, that is the best temperature for babies . I know that can be done with control of TRVs but it just seemed daft that during the week mornings, we're only in the bedrooms or bathroom getting ready for work, but I'm heating the entire house up.

I'm still looking at this as I don't know all the issues (hence this post). I just was hoping that I wouldn't be forced into a system like the Evohome or TADO. Either of those will set me back a lot more than I had hoped, specially since they are still fairly new and probably have bugs that need to be sorted out.

Does any water flow when the radiators are off? I've tried to find diagrams on how central heating is set up but couldn't get anything helpful (for a dumbo like me)

 

[motorbiking]

A quick summary of how it works.. You boiler heats two circuits of water in a closed loop, depending on if you have one or both of the hot water and central heating on. When the central heating is on a valve opens the central heating circuit and the hot water is pumped around that. If you imagine your lungs are like the boiler and your heart like the pump, its very similar, i.e. you have a flow (oxygenated blood) and a return (empty blood). A typical house may have 100-150M (rough guess) of pipe in the flow ant return circuit, that is without the radiators. The radiators take a feed via a junction on the flow circuit and they return the less hot water back on the return, that way you don't get one really hot radiator and then progressively colder as the warm water flows around the house.

If all your rads are closed, the boiler merrily pumps hot water around the circuit, which is situated in your under floor typically. If those pipes aren't insulated and often they aren't, then that 150M of pipe, might be equiv. to something like 4 large rads heating the infrastructure of your home with little benefit to you. That could be costing you £3 a day.

 

[AlanB1976]

Thanks for that.
But if all TRVs are off, then wouldn't that isolate the flow and return circuit (cause the radiators are that only link between them) and result in no water being able to flow? Then the boiler would be trying to pump water down closed pipes and hence nothing would flow, and so the only heating would be the conducting of the still water temperature down the pipe? Am I misunderstanding?

 

[motorbiking]

No - because the rads are plumbed as branches off the circuits. The TRV on the radiator just closes the branch, otherwise the first closed rad would close all subsequent rads:

 

[John D v2.0]

Yes you're right, it would stop the water, but pumps and boilers, as you guessed, have a minimum flow rate to avoid damage. Usually this is fine with either an automatic or standard bypass which could be built in the boiler, or one radiator that's always open ie no TRV.
IN your case, if you really don't want to control the boiler as well, you would save the most by making sure there's a bypass as close as possible to the boiler.

 

[AlanB1976]

Thanks again all. You learn something new every day
It's clear my initial idea won't work as I planned (or at least not without additional expense). I'll have a look again at the full smart systems but might just wait a year or 2 to see how they evolve.

 

[Agile]

They are already there and pretty reliable.

There is unlikely to be any significant developments.