Hi, new member and in need of help with y plan system.

[DirksPlumbing]

This is why with these big boys (boilers) it is better to install a low loss header.
CW

Seen the LLH installation, looks marvelous. But I am not a big friend of them as they decrease the system efficiency by artificially lifting the return temperature and therefore decreasing the condensation effect.

Better is controlled zoning. Honewell does some nice valves to ensure that the zones are getting what they are due. You can then ABV each zone individually to use the pipework as buffer for the boiler output.
(Add: saves adding pumps using electric power)

The 15/60 would struggle on heavy use of microbore already with less than 20kW.

 

[ckgreenall]

Hi Chris
have a look at this post &/or search V.A Heating Ltd they have details.
http://www.ukplumbersforums.co.uk/central-heating-forum/36366-low-loss-header.html

Thanks Chris, that's a good plain English explanation on the low loss header.

We are going for a swap out of the return pipe work tomorrow to see if that is the issue. One other symptom that points towards poor flow is that when ever I go to bleed the tf1, I always get at least 5 secs of air... Which suggests to me that we are not getting enough water return to the boiler.

Cheers,

Chris

 

[RGII79]

Sound like your pumping up vent pipe and loosing flow through return what type of boiler had you got before or is this new install
i always fit pump on the return on a open vent system easier to balance and less problems pitching

 

[RGII79]

Your circulating through one pipe your vent and feed is becoming a circuit

 

[DirksPlumbing]

Hi Dirk, when you say bypass what do you mean?

A bypass is a link from between the pump and the control valve towards the return to have circulation even if the midposition valve is on CH demand only and all TRVs are (mostly) shut.

Nowadays an Automatic Bypass Valve should be fitted. That contravenes the use of class A pumps as the manufacturers state not to use ABVs with them.
But it still works in constant pressure profiles.

 

[DirksPlumbing]

I think if the installer did not know about a bypass he most likely did not know about air pockets and water sacks either rather than proximity fill/expansion.

 

[ckgreenall]

All,

Thanks again for all your replies, its good to get some other opinions as this fuels the thought process. Re the original boiler, it was a Myson Apollo 50/65 which had been in since the house was built around 22 years ago. The only issue we had previously was getting the downstairs rads to come on after the summer and the rads only getting hot at the top which we were told was down to sludge in the bottom. This was the driver to replace the rads and while we were at it put a nice new efficient boiler in...... which to this point hasn't worked properly since installation 4 weeks ago.

Actually, that probably isn't a fair statement... its the system at fault here. The boiler creates heat and it gets to the airing cupboard.. just not much further beyond.

We are swapping out the return pipe later today from the point where the CH & HW returns join back to the TF1 which is just above the boiler and we will go from there. I'll report back later.

Cheers,

Chris

 

[peteheat]

Pipe size appears to be one issue.

 

[ckgreenall]

Hi All, quick update. Replaced the last 5 meters of return pipe and no joy. Also put a secondary pump in place of the tf1 (so pumping direct into the boiler on the return) and exactly the same result. The boiler still reporting no flow, stopping the pump in the airing cupboard and spitting water into the header tank.

I have had a suggestion of power flushing the system. Would this be a good step?

Thanks,

Chris

 

[chris watkins]

Was it not cleaned before the new boiler what in, then ?
It might be a partly blocked heat exchanger ? When boiler does fire how quickly does the flow get hot & to what sort of temp ?

 

[ckgreenall]

Was it not cleaned before the new boiler what in, then ?
It might be a partly blocked heat exchanger ? When boiler does fire how quickly does the flow get hot & to what sort of temp ?

Hi Chris,

The system was cleaned prior to the new boiler being out in but to what standard I don't know. I had thought about a blockage within the boiler so maybe a system flush would cure that. When the boiler fires it gets hot on the flow very quickly right up to the airing cupboard such that you can't keep your hand on the pipes. For the CH the boiler will fire for a good 3-4 mins before it switches off and reports the flow error, however for the HW it will only go for around 2 mins. In both instances we get hardly any heat on the returns anywhere within 8-10 meters.

Cheers,

Chris

 

[RGII79]

blank off f&e pipes and try pressurising system to 1.5 bar and vent all over if ther is no blockage and your flow and returns arent mixed up its a blockage somewhere

 

[ckgreenall]

Hi All,

Ok quick update on this. Yesterday I cleaned out the header tank (which hadn't been done!) and the put 2ltrs of Sentinel x800 into the system and whacked the pump up to 3. Nothing changed over night but came home this evening to the system up and running. Return pipe nice and hot and boiler running away nicely. Just cleaned out the TF1 again and will monitor for next few days.

I am hoping that this has been down to dirt remaining in the system from the install.... Fingers crossed.

Thanks all so far for your input and suggestions.

Regards,

Chris