Baxi Combi 80e, Do I need a room stat??

chrest

I moved into my home last Dec so not overly sure how my boiler works.

It is a Baxi Combi 80e, I have TRV's on all my radiators but I do not have a room stat anywhere. Should there be? Do I need one?

If I dont need one, do I need to have the TRV in the kitchen (where the boiler is) turns up to maximum for the boiler to know the temperature? Or does the boiler just know what the temperature is without knowing the room temperature?

At the moment, I have bedroom and lounge trv's set at 4 and rest of house trv's at 1 including kitchen to try and be as efficient as possible. but I now worrying about how the boiler knows what temperature to reach before turning itself off.

Any advice greatly appreciated.

EliteHeat

I posted a longer reply, but it got lost.

So, the answer is yes you do. It will save you money, increase your control over the system and adhere to current building regulations.

chrest

I was afraid someone might say that. It sounds expensive.

From combing the internet,I have read a couple of times that some Baxi Combi's dont need a room stat so I was hoping mine was one of them. And just that I might have been doing something wrong with the kitchen trv.

Are there any boilers that dont need a room stat? or have I misread something?

jfinnie

I'd check with a plumber. I know a few people with combi's and they don't have a roomstat. On the other hand I just had a new boiler put in and the plumber said I needed one. I think there was a time when it wasn't mandatory to have a stat if you had TRVs in each room - and you don't have to re-visit your heating system every time a new Building regulation comes out.

They are useful; your boiler probably has a very basic 24hr timer (a dial with just a few markers to push in / out to choose when the boiler is on) - more advanced programmable stats will allow you to set quite extensive programs, holiday periods, etc etc over much longer periods. For example if you work during the week, it is pointless having your heating on full blast while you are out of the house - but with only a 24hr timer you can't distinguish between weekdays (when you only want the boiler on in the morning / evenings) and weekends when you probably want it on all day.

Wireless stats can minimize installation costs (no cables to chase around the house) and don't cost a fortune - we had a Honeywell CM927 fitted - cost of stat was less than £100 (you might well save that quite quickly depending on how much you are in the house given the current price of fuel!):
http://www.heatingcontrolsonline.co.uk/honeywell-cmt927-cm927-wireless-programmable-room-thermostat-p-68.html
You do need either a plumber who is happy with electrics or an electrician who is happy with boilers to put it in - but if shouldn't take any more than an hour to install.

(edit - just found this)
For an existing boiler, this one looks even better (and just replaces your existing timeclock!)
http://www.heatingcontrolsonline.co.uk/wireless-plugin-programmable-thermostat-for-combi-boilers-p-350.html
http://www.tfc-group.co.uk/~sa_webapp/run.asp?page=279
They seem to be implying it just plugs in.

I would say just a basic room stat wouldn't give you much over your current TRVs - other than quickly being able to turn off the heating by winding it down.

I am neither a plumber nor an electrician, just my recent experience. Hope it is useful to you.

moneysavingplumber

Just to echo EliteHeat, it is advisable to have a room stat fitted on heating systems.

The boiler doesn't sense the heat in the room, if it's switched on into heating mode it will simply cycle on and off in response to the heat within the boiler, when it cools down it will switch back on, so if all the TRVs are closed the water will simply cycle around the bypass (assuming one is incorporated or has been fitted) until it cools down, which will increase wear on the pump unnecesssarily and simply waste energy. Once a room stat is satisfied it will switch the heating off completely until the room temperature drops.

Personally I would go for a hardwired Honeywell room stat with the mechanical timeclock fitted on the boiler. If you're happy to have trunked cable surface mounted it won't cost a fortune to have the it fitted as it wires straight into the boiler, provided the ideal site for it isn't too far away from the boiler. Drayton RF1 is a good wireless stat but the receiver will have to be mounted somewhere and they are more chunky and the batteries have to be replaced every couple of years.

As EliteHeat states, this will also conform with Energy Efficiency building regs.

http://www.energysavingtrust.org.uk

Document CE51 covers recommendations and requirements for heating systems, a timer and room stat with TRVs, bypass and a combi will bring your system to specification 'HC6' which is best practice.

SootSoot

DH installed a new wireless thermostat on our potterton (same as a baxi different label). Its brilliant and easy to install and under £80. It fits in the same place as the timer dial and works the same as any wireless thermostat.
We got ours off Ebay as it was the cheapest there and there aren't many stockists. Its a Towerstat RF-BM and from reading it is compatible with your boiler.

HTH.

Ooops just clicked on jfinnie's links and its the same one that we have.

moneysavingplumber

The Towerstat RF/BM is similar to the Alpha Easy-Stat which was the first wireless stat just for combis. They are great from an intallation point of view and fine if you don't mind going through the set-up process again when the batteries fail in the remote unit.

The advantage of a hardwired stat is that once fitted they will be maintenance free and usually outlast the boiler several times over.

Just as a note the MI on these units always state that they must be fitted by a qualified person.

jwturpin

I too HAD a baxi 80 boiler, with TRV's on my radiators, and no room stat. V.inefficient!!
A TRV senses the room temp in which it is located, and increases or decreases the flow of water to that particular radiator. If the whole house is warm, and all your TRV's switch off, the the water from the boiler just flows round and round in a big circuit, which of course, will make it get very hot as the heat isn't being dispersed through the radiators. There is a stat in the boiler which will sense this and switch the heat off, but the PUMP KEEPS GOING! tut tut tut! V.inefficient also! and increases wear and tear!

Obvioulsy, as your rooms cool down and the TRV's increase the flow back to the radiator, the circulating water suddenly cools down again, and the stat in the boiler turn the flame back on again...blah blah blah, you get the idea i'm sure.

I now have same said boiler, WITH a towerstat RF-BM. Installing one of these devices mentioned in previous replies (towerstat RF-BM) will monitor the air temperature in an average space in your home, and when the air reaches the desired temp, it actually turns off the boiler, flame, pump, everything. yay! more efficient, as your boiler is no longer heating circulating water for the sake of it, which to be fair, it would do, for ever and a day, unless you manually turned it off, and thats where the wasteage comes from. Especially if you have a crappy mechanical timer with a ring of little dip switches, I used to set my timings up, and if I forgot about, and it was a particularly warm day, the boiler came on. Mad!!

I have noticed a decrease of 12% in my gas bill since installing it (thats 12% decrease in unit consumption , not cost - but hey, if I hadn't installed it, the cost would be way higher than it is now after the price rises!)

blurb over.