Heating / Plumbing questions Thermostats TRV

brownbake

Hi,

Just a few questions regarding thermostats and TRVs. Our boiler seems to work fine albeit old and we have it serviced annually.

However when the heating is on it is hot and we have no control. The room thermostat is old dial type and only seems to go on at a click and then I don't think the other functions change the temperature.

Here is a pic of it
http://i169.photobucket.com/albums/u206/booksgreatoffers/Copyofroomthermostat.jpg It is wired. I was wondering if we could fit one of these types http://www.toolstation.com/shop/Plumbing+Heating/Controllers/Salus+Programmable+Room+Thermostat+Wired/d20/sd2732/p41715
and would we have more control?

We also have these types of rad valves
http://i169.photobucket.com/albums/u206/booksgreatoffers/radpipes.jpg
have included a pic of a pencil for comparison to supply pipes - apparently they are micropipes? We would like to add TRVs to all rooms. Does anyone know what type / size we would have to get based on the pic and also how much a plumber would charge to fit. In total there are 6 radiators.

Any help or advice would be greatfully received and we thank you in advance.

jblack_2

The room stat may be compatible. It depends on the boiler. The best thing to do is contact the manufacturer.

You have microbore pipework. You can fit pretty much any TRV you like. You will need to use reducing olives though as most are 15mm as standard. I normally use the Danfoss combi type, good quality.

J

brownbake

Thanks for your reply. The boiler is an old one from the 70's an Ideal Concord W but still working OK so will get in touch with them tomorrow to ask about the room stat.

Could you let me know where to get the Danfoss parts mentioned? Are these good TRVs - we don't need anything too fancy or expensive. Just controlable, reliable and fit and forget really.

How much do you think a plumber would charge to fit 6 TRV or alternatively how long is it likely to take - 2 hours?

Thanks

EliteHeat

The programmable room thermostat is completely compatible with your boiler, since this neither knows nor cares what is switching it. You new thernmostat will work OK as long as you do NOT have a gravity hot water circuit - i.e. you need full independant control over heating and hot water.

Your current wiring is not directly compatible with the new unit. You currently have a 230V switch which will probably have a live, switched live, neutral and earth connection.

The new unit just uses live and switched live and will rely on the programmer being permanently switched on for central heating, or the heating function channel being bypassed at the wiring centre. You will need to identify the live wire and connect this to the thernmostats 'common' connection, the switched live is then connected to the 'NO' (normally open) connection. The neutral and earth wires must be made safe.

If you are unsure of any of this or are not competent to work with mains wiring or do not understand how heating systems work, then I would advise you to get a decent heating engineer in to sort it out for you.

latecomer

If you are DIY minded then changing the radiator valves for TRVs is not that big a job. I did the same thing to our system earlier this year and also moved a radiator. I added a flushing agent to the system a couple of days before doing the work and while the system was drained down I took all the radiators outside and flushed them with a hose to clean then out.

The main thing to be careful of is the pipes as they are very flexible compared with normal 15mm copper pipe. You need to remove the old valves and olives, clean up the pipe and then install the new valves. I did everything within about 7-8 hours but was working on my own for a lot of that.

I've no experience of changing the thermostat but as EliteHeat says mains wiring is not something to mess with if you dont konw what you are doing. Water gets you wet, electricity kills.

brownbake

Thanks for your replies. Me and my big ideas - I thought the room thermostat would be just a case of direct switching like a light switch or socket - which I can manage.

It seems a bit more complicated than that lol!!

Yes I am DIY minded but not that experienced. I assumed that the TRVs would be quite simple to change but sounds a bit more complicated. We have very good heat to the radiators - it gets too hot if anything so that's why I wanted more control over the heating instead of just on or off.

Seeing that we have almost finishing decorating and removing rads is gonna be messy I will have to skip that stage. Is flushing done just to remove the debris and muck build up to improve effeciency? As said the rads work very well - just the hot water flow is rubbish in the kitchen taps - bathroom is pumped.

But we are replacing kitchen tap so hopefully this will help. Rabbitting, sorry.

We also have very hard water - does anyone know if those limescale removers / decalcifiers actually work or are they a gimmick? Seen one here

http://cgi.ebay.co.uk/Decalcifier-Descaler-Hard-Water-Limescale-Remover_W0QQitemZ110310001003QQcmdZViewItem?hash=item110310001003&_trksid=p3286.c0.m14&_trkparms=72:1301|66%3A2|65%3A12|39%3A1|240%3A1318

Thanks for all your help and advice so far.

Broadsword

Latecomer's advice is absolutely sound and is the "gold standard" way of doing it. If you do want to do it the easy way, drain down the system, making sure the heating is off and not programmed to come on, flush water through (by turning on the supply to the header tank again) and change each valve. In three properties where I have done it, the TRVs were a straight swop and I even re-used the existing olive rings on the pipe. The rings can be very hard to remove without damaging the pipe, so if its leak free you're fine. I did use some turns of PTFE tape to make sure (on the threaded parts only). So, if you're lucky, you'll be able to do it without too much fuss by a straight swop. Don't whatever you do overtighten the unions, if you have any small drips later you can always give the joint an extra little turn

After completion refill and air bleed the system, turn on and check for leaks. Then drain down again (yes it's a bore to do) and then add some anti corrosive (Fernox etc). The reason you do it this way round is if you add the Fernox at first refill and you have a leak, you lose £14-20 worth of stuff when you ndrain it down to fix the leak

latecomer

I would recommend using PTFE on all threaded connections and also a turn or two over the olive, just to be on the safe side.

Also as Broadsword said, its very important to add the inhibitor once you've finished (something I've not yet done since having the system drained last week but need to do this weekend)

Devon_Hippo

In fact, it is not correct to use PTFE tape on threaded connections. It is fine to use it on the olives if you feel it is needed, and I always give an olive a wrap of tape myself actually.

A compression fitting, by its very name, use compression to seal the connection, the nut presses against the olive driving it towards the coupling. When the olive meets the coupling and can go no further then you start making a joint/seal the sqeezing of the olive causes it to distort at its edges and 'bite' the pipe and rise in the middle and contact the coupling inner face (have a look and you'll see the coupling is quite smooth in there).

So if we put PTFE tape on the threads, we now need to compress and get by a lump of PTFE tape before we can even start to compress the olive (and remember the olive is the jointing component here) so you're not getting to the olive with full grunt, you could even believe you've got a tight fit as you'll be adding the effective resistance of the PTFE tape plus the force required to deform the olive together and 'kidding' yourself resulting in a leaking joint.

angelavdavis

brownbake wrote: »

Seeing that we have almost finishing decorating and removing rads is gonna be messy I will have to skip that stage. Is flushing done just to remove the debris and muck build up to improve effeciency? As said the rads work very well - just the hot water flow is rubbish in the kitchen taps - bathroom is pumped.

It is really recommended that you flush out the system somehow to remove the build up. It is worth doing this if you have installed new radiators, etc. Latecomer's suggested removal of the radiators provides a good DIY manual solution. You can also get someone in to powerflush the system (controversial although this appears to be looking at some of the threads about the prices quoted for this service offered by some companies).

From doing this myself, I personally would recommend some of the following tips to minimise the mess:

- Ensure you have made up two male flanged plugs that unable you to shut off the radiator valves as very often, even shut off, these will leak slightly, so when you remove the radiator, you can shut these off. This enables you to leave the rad off overnight or for a few days if necessary.
- Put old carrier bags fixed with elastic bands over the radiator valves after bleeding before moving the radiator to ensure that the residual muck/fluid doesn't drip everywhere!

As far as the kitchen tap flow is concerned, I haven't used a decalcifier before, thought the new tap might help. Is the hot water gravity fed?

jblack_2

Devon_Hippo wrote: »

In fact, it is not correct to use PTFE tape on threaded connections. It is fine to use it on the olives if you feel it is needed, and I always give an olive a wrap of tape myself actually.

No.

The threaded part of the TRV which goes in to the radiator always needs PTFE. It isn't a compression fitting.