Central heating - but no thermostat?

Tom B. Stones

Hello.

Can anyone tell me if the following situation makes sense (or not)?

A house built (self-build/direct labour, so may be a bit weird in ways) in 2003-04 has a kerosene boiler and radiators.

There is a very basic "timeswitch" (with a push-in "peg" for every half hour in a 24 hour cycle).

There is a light switch (!) to chose between heat-plus-hot-water and hot-water-only.

The radiators have thermostatic valves.

However, the system seems to have no thermostat for setting a desired temperature.

Should the system not have a thermostat?

And should a system installed as recently as 2003 have such a primitive timeswitch? - or some sort of digital programmer like this?

Many thanks.

- Tom

towbar

I would have thought with thermostatic valves you wouldnt need a room stat. There will be a water thermostat on the boiler. Make sure there is a least one radiator with a fully open non thermostatic valve which acts s a bypass if all of the valves closed. As for the light switch and old fashioned timer, I saw a house where the digital one had to be ripped out and one as you described put in as the tenants were both blind but could use the peg style stat! Cant see anything wrong with a light switch fitting provided its clearly marked but dont know if there are any electrical wiring compliance issues.

chuckles30

I would have thought that radiator thermostats were even more accurate than the regular thermostat - that way you can set the temperature in each room, rather than for the whole house. I bought a new house only built this year and only have the regular 'peg' timer clock. To be honest I think it's great - it's easy to use and you can see at a glance when you're heating is on and off. I regularly use a digital time similar to the one you refer to in a church that I'm involved in looking after and it can be a complete pain. It's great if you don't need to change your settings regularly, but I wouldn't want one in my house. Plus, I would consider myself fairly technically minded and even at that it took me a while to get used to it.

Tom B. Stones

Thanks, fellas.

Very interesting - and encouraging (we're considering making a home in the place, and it's a big case of beggars can't be choosers).

The thermostatic valves on each radiator (and there isn't a rad without such a valve, towbar ) don't let you chose a temperature as such. Each valve's knob is numbered 1 to 5 - and those are the choices.

Should the boiler (or its controls) not have a thermostat as well?

towbar

The numbers on the thermostatic valves allow temperature setting. Set valve at 3 say and when rooms warms up you'll find radiator may actually go cold as valve turns it off.

As far as I know you need to pick one radiator and leave the valve open full (black dot) unless a bypass valve has been fitted which I doubt.. A hall for example would be ideal. If it is too hot you could close the valve on the opposite side a little bit.

The boiler should have a water thermostat on it somewhere that sets the temperature at which the boiler cuts out otherwise boiler would run continuousily.

Tom B. Stones

towbar, many thanks indeed. You have been most helpful.

The radiator valves do have black circles (at one extreme - and "snowflake" type symbols at the other), so that sounds like it should do the trick.

I have not been able to spot a thermostat on the boiler (but I'm no expert!). I expected to find something with which we ourselves could manually choose the max temp (at which point the boiler would stop running). But what you say makes sense. Must have another look if we can get at it at the weekend.

Thanks again.

towbar

snowflake is frost mode - radiator turns on if temp below 5 degrees or something like that.


Must be a thermostat on boiler - might be just numbers as well rather than degrees, but it will be an adjustable dial. The boiler wouldnt work without it.

JamesM

towbar wrote:

snowflake is frost mode - radiator turns on if temp below 5 degrees or something like that.


Must be a thermostat on boiler - might be just numbers as well rather than degrees, but it will be an adjustable dial. The boiler wouldnt work without it.

Yes almost certainly a stat on the boiler - maybe a dial with a line that goes from narrow to wide. It can be in a panel on the front of the boiler, sitting on top of the boiler or on the top outlet pipe very close to the boiler. If you hear the boiler going on and off, it is there.
Jim.

Tom B. Stones

Thanks, fellas. Much appreciated.

Didn't get at it last weekend, but now hope to this coming one. I'll have a look for something along those lines.

The boiler can indeed be heard going on and off. I thought that this might be influenced by the thermostatic valves on the radiators.

JamesM

Tom B. Stones wrote:

Thanks, fellas. Much appreciated.

The boiler can indeed be heard going on and off. I thought that this might be influenced by the thermostatic valves on the radiators.

The thermostatic valves cannot do it - there is a boiler stat somewhere. If it has temperature markings, start at 60 and go up as you need more heat.
Jim.

GreeBo

my boiler doesnt seem to have a user changeable stat
There is a high/low switch but thats it
unless its hidden under the casing somewhere...
I had considered that the switch might be for the pump, but the boiler kicks into life if the switch chnages from low to high so...

JamesM

GreeBo wrote:

my boiler doesnt seem to have a user changeable stat
There is a high/low switch but thats it
unless its hidden under the casing somewhere...
I had considered that the switch might be for the pump, but the boiler kicks into life if the switch chnages from low to high so...

Is it gas ? I have never seen an oil boiler without a stat.
Jim.

GreeBo

yeah its gas...
Ideal Compact..
cant find any documentation for it though...

flocker

Documentation maybe available here ideal boilers

serotonin_sam

Every boiler has a thermostat - without it, it would blow up!
Thermostatic Radiator Valves (TRV's) can be used to set the required temp. in each room. However, they do not prevent boiler cycling. This is where a 'boiler interlock' comes into play ie. wiring the boiler up to another thermostat (most probably located in the main living area of the house - say the lounge/living room) and making sure that 'stat is the first one read off the system.

This is far more efficient as the boiler is smart enough to shut down the moment the 'stat in the living room tells it that its reached the ideal temperature.
The most efficient system of all would be zone control - where two areas of the house are on seperate heating circuits with 'stats located in each area linked back to the boiler.

I have a similar system as the OP (despite mine being built '05-'06). If there is ever an opportunity to change this without major expenditure, I will be doing it. I would have thought there should be a way for someone to produce a wireless 'stat that could be linked in with the boiler?


As an aside, you may be interested to know that when existing dwellings are assessed for energy efficiency (from 2009 onwards), TRV's (to a marginal extent), a boiler interlock (to a greater extent) and zone control (the most efficient of all) will improve your dwellings BER energy rating.

JamesM

serotonin_sam wrote:

Every boiler has a thermostat - without it, it would blow up!
Thermostatic Radiator Valves (TRV's) can be used to set the required temp. in each room. However, they do not prevent boiler cycling. This is where a 'boiler interlock' comes into play ie. wiring the boiler up to another thermostat (most probably located in the main living area of the house - say the lounge/living room) and making sure that 'stat is the first one read off the system.

This is far more efficient as the boiler is smart enough to shut down the moment the 'stat in the living room tells it that its reached the ideal temperature.
The most efficient system of all would be zone control - where two areas of the house are on seperate heating circuits with 'stats located in each area linked back to the boiler.

I have a similar system as the OP (despite mine being built '05-'06). If there is ever an opportunity to change this without major expenditure, I will be doing it. I would have thought there should be a way for someone to produce a wireless 'stat that could be linked in with the boiler?


As an aside, you may be interested to know that when existing dwellings are assessed for energy efficiency (from 2009 onwards), TRV's (to a marginal extent), a boiler interlock (to a greater extent) and zone control (the most efficient of all) will improve your dwellings BER energy rating.

I may be misunderstanding what you are saying, but, if you have a similar system to the OP, you should never link a room stat directly to the boiler. It should either control the waterpump (in simple systems), or a motorised zone valve. The boiler must always be controlled by its own stat. Maybe you are saying that the boiler stat is also in the circuit ? That will take care of safety, but no good if you are heating your hot water from the boiler. When the room heats up, the stat switches off the boiler - no hot water. If the water pump is also switched off - no hot water. If the water pump keeps circulating, you are circulating cool water to the hot water cylinder, cooling it down.
Once the system is on, The boiler must always be kept up to temperature, keeping the water hot and ready to heat the rads when needed.
Jim.

serotonin_sam

JamesM wrote:

I may be misunderstanding what you are saying, but, if you have a similar system to the OP, you should never link a room stat directly to the boiler. It should either control the waterpump (in simple systems), or a motorised zone valve. The boiler must always be controlled by its own stat. Maybe you are saying that the boiler stat is also in the circuit ? That will take care of safety, but no good if you are heating your hot water from the boiler. When the room heats up, the stat switches off the boiler - no hot water. If the water pump is also switched off - no hot water. If the water pump keeps circulating, you are circulating cool water to the hot water cylinder, cooling it down.
Once the system is on, The boiler must always be kept up to temperature, keeping the water hot and ready to heat the rads when needed.
Jim.

OK - I am not a heating engineer. However, my understanding is that IF the system has a 'Boiler Interlock', the system is deemed to be more efficient. My understanding is that both 'stats would be on the circuit - but the living room stat would be first off the circuit. Surely the hot water would be kept hot on the basis that once the living room stat fell below the preset level, the boiler would kick up again - and the hot water would circulate??

I dont know how this would work but such systems are definitely available and commonplace. Maybe someone else can come on here and explain exactly how it works?

sjc

I've just had a similar discussion with my plumber and electrician regarding this because of the design of our heating system.

Our new build has UFH downstairs that will hopefully run mainly on solar, and radiators upstairs that will run on an LPG boiler. I had never seen a modern central heating system without a zoned (whether one, two or more) thermostat before the house we are currently renting, so I asked the electrician where ours was going. I was a bit shocked to find that the plumber told him we didn't need one, and that he was only uses TRVs as the control.

What this would mean is that the boiler would always cycle if the timer was on no matter what the temperature in the house until the boiler hit it's cut off point. Our boiler is in a boiler house 40 feet away so would not even benefit from having the warmer start it would get in the house. I don't know how long it would cycle but I had no intention of heating and pumping hot water through my house if I didn't need it. With the UFH downstairs, and what I hope is very good insulation all over, I don't think (hope) the rads would come on for no more than a few weeks of the year.

Basically, our plumber is a bit old school as a zone thermostat should mean a more efficient heating system because your boiler doesn't waste energy heating unnecessarily. If you use TRVs the boiler won't blow up as it has it's own thermostat built in.


As an afterthought a gas advert from last winter has just sprung to mind. The one where they say you would cut your bills by 10% by turning your thermostat down 1 degree. Without the zone thermostat you won't have the option. You can still keep TRVs on rads (I think they are mandatory now anyway but could be wrong) to keep some rooms cooler but your overall temp is capped.


So I don't bore you any more, just one last thing.
We had heard of people keeping their central heating on 24/7 at a constant temperature as it was supposed to be more efficient than heating the house up from cold every few hours. We experimented with it last winter and it worked for us. We set the thermostat at around 19 degrees and left it on continually with a small adjustment made at night to around 17 degrees. House was much more comfortable without the heat fluctuations. I was at home looking after our toddler so was great for the both of us. Gas had just had it's huge price hike so not totally sure, but I think any increase in the bill was marginal. Previously, we had the CH running for two hours in the morning and evening with a couple of boosts whenever we felt the need.
This experience had me sold on the UFH in the new build. As you have less temperature control than radiators due to the rate the slab heats and cools the idea of running water through at 25ish degrees instead of 60ish for rads seemed to make sense. Will let you know how it goes when we try it out properly next winter.

JamesM

serotonin_sam wrote:

OK - I am not a heating engineer. However, my understanding is that IF the system has a 'Boiler Interlock', the system is deemed to be more efficient. My understanding is that both 'stats would be on the circuit - but the living room stat would be first off the circuit. Surely the hot water would be kept hot on the basis that once the living room stat fell below the preset level, the boiler would kick up again - and the hot water would circulate??

I dont know how this would work but such systems are definitely available and commonplace. Maybe someone else can come on here and explain exactly how it works?

I would not like to have a system where the amount of hot water I have available depends on how hot my living room gets. If I light a fire in the living room, I have no chance of a shower or a bath. I know that there are many new systems now available, combi, condensing, all kinds of boilers. But if you want domestic hot water from your heating sysem, you have to have hot water in your boiler.

SJC, It would seem that your system does not heat your domestic water at all. Also, if your boiler is 40ft away from your house, I hope that you have paid a fortune insulating the pipes, or it will cost you a fortune to run, especially with lpg which is the most epensive fuel availale.
Jim.

sjc

Sorry, missed that bit out. There are two 300l tanks in the boiler house. One each for the hot water and heating. Piping to the house is super insulated.

I'm more concerned about winter supply as summer will obviously be no problem so have have slightly increased the solar area than what most of the suppliers had suggested. We have a small family and so hot water supply shouldn't be a problem. On a day like today, cloudy and overcast in Carlow, the tanks should still hit 40+ degrees and if used properly the UFH should need little top up from the boiler.

LPG, as you say, is expensive and my main concern. Decided to go for it as the cooker and one fireplace will use it. Hoping the insulation does the job and neither the fire nor the radiators will be on very often. If our sums turn out wrong I'll be pumping more insulation into the walls as a first step and then looking at another boiler.