twin boiler install - this cant be right can it??

[ShaunCorbs]

I'd say longest run of 22mm is likely 30m or so to the last rad on the run.

As far as I'm aware it's 22mm flow, 22mm return and tees off in either 15mm or 10mm for each individual rad.

for a start them (internal) pumps wont do anything that far you might be ok with the pipe work under the floor but i would recomend on upping where you can see it eg where the boilers are and fit a low loss header and bigger pump/pumps

 

[CChris]

Furthest radiator away from the boiler does get hot though. And fairly quickly. I'll run an acid test with the lot on full bore and see what happens.

 

[ShaunCorbs]

Furthest radiator away from the boiler does get hot though. And fairly quickly. I'll run an acid test with the lot on full bore and see what happens.

its when everything is calling eg underfloor rads cylinder if you can test and turn all of it on go for it

 

[CChris]

I should be able to do that some time tomorrow. Will run off a load of he HW after everyone's showered to make sure the cylinder is also calling when I test.

Though no idea if the under floor is actually doing its job and sucking heat into the slab. Trying to get this to work on its own this evening was a failure.

 

[ShaunCorbs]

Don't have a clue regarding the underfoor as I don't do it maybe ask one of the lads in here if you can manually open it 1/2 to get some heat through it ??

 

[CChris]

Results of test are not good.

Woke to a cold house and no hot water. Boiler showing L1 fault. Overheat lockout.

I'm guessing this is because I closed the valve to underfloor heating and switched that off. As per a previous post there is no bypass as advised in the installation manual. So when the heating shut off last night, all valves were closed and the pump overun had nowhere to go.

Took the opportunity to whip the trv heads off all rads, ensure pin was moving and open the other ends. All rads fully open. Whacked the thermostats up to full and set the hot water on boost. An hour later and some rads are still cold. Notably the furthest ones away.

I accept this is a little unfair test as normally those that have got belting hot like the small one in a walk in wardrobe would have shut off by now and not be taking heat from the system. But still for the furthest ones away to still be cold is not great.

Either pipes undersized or pump not adequate?

As I can get the furthest one away hot if I turn others down, then it seems I can get heat to it, but the pump just isn't capable of doing all the rads at the same time. Does this sound plausible?

Is a low loss header and external pumps the solution? Or is the belt and braces method to uprate the pipes?

Some rads are fed by microbore, 8 of the currently switched on 20. With a further 6 plumbed with microbore but not yet connected. All in 15 plumbed with 15mm and 14 with microbore when all done. Anything untoward here?

 

[chris watkins]

Can I ask where the designs for this system are, the heat loss calculations, pipework sizes etc ? Surely you must have seen these before you employed the builder & the work started.

This is clearly no ordinary 3 or 4 bed semi, so why would not alarm bells not be ringing long before now, you clearly have experience in property development, it just seems very strange why you would just rely on a builder/plumber to provide heating / hot water for such a place.

As before, you now need someone (a design engineer) to come in see what should be there, what has been installed, talk you through the options, prepare a report that you can present to the builder setting out the corrective works required. etc etc. (just withholding money without this is not an option, he will take you to court)

Yes it is going to cost money, with all due respect, it can not be done on a plumbing forum & by you but it sure as hell will cost you a lot more if you don't employ an expert !!

 

[CChris]

Nope not a property developer, just have a builder friend that I've bought houses off plan from and I know it's quality stuff. Sadly he was too busy for my own personal house extension.

I didn't see calcs. Though I'd did design where I wanted radiators. I trusted the builder who has done large commercial stuff before and the plumber to do their jobs. I did not have time to micro manage the build, and as I'm no heating engineer just assumed (there's the big mistake) that these guys knew what they were doing.

I've got ano engineer coming to assess the situation on Monday.

I haven't been living at the property while work has been taking place, so have been unable to test all these elements in any real life scenarios until now.

Done my own totting up of the radiators and it totals 71,592 btu upstairs, before I add on the four large towel rads. I'm going to take a wild stab in the dark that 22mm as a feed to this zone isn't going to cut it.

Fully aware what I'll need to present to the builder. I've asked the plumber for design calcs to prove what was installed was/is correct.

 

[chris watkins]

as a guide (& we work in Watts not BTUs now, have done for 30years)
15mm = 11000
22mm = 23000
28mm = 40000
35mm = 62000
@ delta T 20deg C

Best of luck CChris

 

[ShaunCorbs]

as a guide (& we work in Watts not BTUs now, have done for 30years)
15mm = 11000
22mm = 23000
28mm = 40000
35mm = 62000

Best of luck CChris

Unless your old school 😀 tbh I still work kw but converts for the boss as he only works in btus 😀

 

[CChris]

Several calls and emails from plumber and main contractor today.

Turns out some of the rads are oversized for asthetics as they took out some fairly large single panel rads from the 60s that stretched a window and have replaced with similar size but modern. Also he's removing five rads from the upstairs circuit and putting onto their own separate run to remove further loads from the upstairs circuit.

Also going to alter boiler pipework and sort out a bypass, fit all remaining rads etc.

Main contractor and plumber on site all day Monday and they have been tasked with demonstrating the system working as it should.

Can I book snow or at least a good frosty day for Monday please? 🙂

I may be light hearted about it, but seriously ripping the carpets and floors up to replace pipework in the future if it needs it seems just like trivial bit of upset after the build itself. We were supposed to be home end of November 2014 if that gives an indication of how farcical this process has been.