Baxi 105HE TRV's

[davecdti]

Howdy Chaps.

I've got a Baxi 105HE with currently only a roomstat and am looking to install TRV's on 5 of the 6 rads in our house.

I got a local plumber out to quote for supply and fitting and he wanted £230 (which sounded a bit steep when screwfix have valves starting at £5.99) and he reckoned it would only take an hour because all the rads are less than a year old and it would be easy to drain/refill being a combi. Is this a fair price? Or am i being too critical!?

I've now started looking at doing to job myself. But have a fair areas of uncertainty...

1) Is this a job a DIY'er should undertake? Is there a risk of damage?
2) How do i drain this system? From the boiler, or from the furthest rad?
3) How do refill the system?
4) Which side of each rad does the trv need to be fitted to (in/out). And how do i determine that side?

Anything else i should know?

Any help greatly appreciated.

Cheers

Dave

Edit, i got the manuals for the boiler if that helps...

http://www.baxi.co.uk/docs/Baxi_Combi_105_HE_User_Instructions.pdf
http://www.baxi.co.uk/docs/Baxi_Combi_105_HE_Installation_and_Servicing_Instructions.pdf

 

[gas4you]

I don't think the price is far out, but the idea that it will only take an hour is very optomistic.

Make sure he adds new inhibitor to the system when refilling.

You can easily DIY this.

Look in FAQ's for how to do it. I'm sure it's all in there.

 

[diy]

(which sounded a bit steep when screwfix have valves starting at £5.99)


will they work though!

 

[davecdti]

(which sounded a bit steep when screwfix have valves starting at £5.99)


will they work though!

Exactly. I was advised by a mate to get a decent trv that had changeable internals without changing the entire trv (should it go faulty). But even so a reasonable one is max £15 which still leaves me with a £155 labour bill.

My main reason for doing this was to try and save a few quid on gas... But with the best will in the world realistically i reckon it's only gonna save me £20 a year....... I'd have to live in my house for another 11 years before i saw a saving... So it's not worth doing. That was the reason i'm leaning more and more to doing it myself.

I've scoured the wiki/faq section, and that has helped. How do i add inhibitor back into the system when refilling? Is there a special way of doing this?

 

[gas4you]

Before fixing the new trv to an upstairs rad pipe, just pout the inhibitor down the pipe. (making sure all the downstairs ones are finished and done up tight)

 

[davecdti]

So... Here goes...

1) Turn off power to boiler
2) Drain the CH system from downstairs rad furthest away from boiler (with bleed valves open upstairs)
3) Fit TRV's to downstairs rads
4) Pour inhibitor into system from upstairs pipe
5) Fit trv's upstairs
6) Close bleed valves
7) Refill system by opening the filling loop
8) Bleed rads of air and add pressure from filling loop if required


does that sound about right?

 

[gas4you]

Yep, I think you've covered most things there

The only thing i would add would be that when you first turn on the boiler again, put the ch boiler stat down fairly low and after about 20 seconds or so turn off the ch.

Hopefully the pump will keep running without the burner on.

This will help get any air out of the HE before it gets hot. I always like to try to remove any possibility of the HE having air in it and burning dry

 

[swbjackson]

Keep some old towels handy. I always put on old towel round the pipe when swapping valves in case you hear the dreaded gurgle as some trapped water releases itself.

Mike

 

[davecdti]

Yep, I think you've covered most things there

The only thing i would add would be that when you first turn on the boiler again, put the ch boiler stat down fairly low and after about 20 seconds or so turn off the ch.

Hopefully the pump will keep running without the burner on.

This will help get any air out of the HE before it gets hot. I always like to try to remove any possibility of the HE having air in it and burning dry

If there is air in the boiler pump or HE should that purge/bleed itself out, or do i need to do anything? I'm a little scared that this is the wrong time of year to be left without CH overnight! It's freekin cold out. lol.

 

[davecdti]

Keep some old towels handy. I always put on old towel round the pipe when swapping valves in case you hear the dreaded gurgle as some trapped water releases itself.

Mike

I'll take that onboard. Cheers

 

[gas4you]

if you follow what I've said, you should have no problems with air. It is just me being extra cautious after filling up.

But then there is always that million to one chance of the unexpected

 

[namsag]

Can you put a picture of your existing valves .
Rads a year old and boiler a HE so why where the valves not fitted with either the boiler or when rads where done as they should have been.
It can be quite easily done without draining the system

 

[clf-gas]

Out of pure interest Nam, how do you do it without draining a pressurised system, besides freezing.

 

[swbjackson]

Just release the excess pressure, shut the other end and it acts the same way as if you've used a bung kit in an open vented system. Worth it for a single valve change but I'd still drain down to change them all.

Mike

 

[namsag]

clf there are 2 ways
and both are exactly the same principle as bunging a system.
First in the case of this boiler 105he its just a case of turning off the boiler isolating valves(which dont leak) and releasing the pressure in the system either theough a bleed nipple or stickin hose on d/cock which will run for a matter of seconds before the vacum is formed allowing valves to be changed.
Second if its a boiler that has dodgy isolating valves that will leak or no valves as in certain system boilers its just a matter of screwing down the caps on auto airvents so the vacum can be held. Then dropping the pressure again.