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

[CChris]

I know its replying to my own thread, again, but am I missing a boiler bypass here? if all four electronic zone valves are shut, I see no route to discharge the residual heat. Or am I missing something obvious as a novice?

EDIT: found the following in the installation guide for the boilers:

"However, if the system employs thermostatic radiator valves on all radiators, or two port valves, then a bypass circuit must be fitted with an automatic bypass valve to ensure a flow of water should all valves be in the closed position."

AND

"Systems incorporating zone valves which could completely cut off the flow through the system must also include a bypass."

As I have TRVs on all rads, and zone valves which could cut off the flow in all directions, Im assuming this applies to me and a bypass needs to be fitted?

 

[tolly]

That Primary flow looks 28mm to me, not 35mm like you've written in the pictures?

 

[ShaunCorbs]

not too bad install a few mistakes and tolly is right its 28mm

 

[CChris]

Can you advise on the "mistakes"?

Had the underfloor on for 4 hours now and it's not even thinking about getting warm. Flow pipe to the manifold is hot, return is stone cold. Manifold is warm, two flow pipes to the kitchen zone are also warm, but their respective returns are stone cold. Do the little things in the top of the manifold signify flow rate through those pipes? If so, there's no flow through them.

Yep you are right it's 28mm not 35. Could the 22mm take the theoretical 60kw from these two boilers?

 

[Chalked]

Needs check valves on return. The boilers will develop a pump flow fault, as it will not get a pressure increase on strt up. Caused by one boiler reverse circulating through another..

 

[ShaunCorbs]

Can you advise on the "mistakes"?

Had the underfloor on for 4 hours now and it's not even thinking about getting warm. Flow pipe to the manifold is hot, return is stone cold. Manifold is warm, two flow pipes to the kitchen zone are also warm, but their respective returns are stone cold. Do the little things in the top of the manifold signify flow rate through those pipes? If so, there's no flow through them.

Yep you are right it's 28mm not 35. Could the 22mm take the theoretical 60kw from these two boilers?

the pumps working on the under floor systems? and could you post a pic up as it sounds like a valve is shut/not open full if you have heat by the manifold

 

[buckley plumb]

could need bleeding all air out.

 

[CChris]

Here's the manifold etc. I believe one issue was the zone valve not being wired in for the underfloor heating. It was mostly shut, so very little flow to the manifold, but enough to get the flow pipe hot.

Manually set this to open and flow to the manifold is now fine.

Pump on the manifold appears to be working fine.

I'm only trying to heat one of the two zones controlled by this manifold, that's fed by the two pipes on the right.

I can feel the two pipes get warm, but flow meters on the top only ever show one of them moving, up to about 2l/m the other doesn't budge.

I tested putting the other zone on so that the other 3 pipes were in action, their flow meters didn't move either. Only ever the second one from the right (which can be seen in the picture).

The manifold itself on the flow side got very hot. I'd say not far off the temp of the flow pipe from the boiler. Thermostat on the left set just pas the 40. I assume this can't be right and I most certainly don't want to be sending 80 degree water into the under floor. So switched the lot off.

Any ideas on this one? I seem to be fighting numerous issues here.

 

[Nostrum]

This is why systems get commissioned, why hasn't it been done by the installer?

 

[chris watkins]

I hope you are holding a large retention on the Builder CChris cos you are going to need it to pay for the corrective works.

You have established that it is not working & not installed correctly so strongly recommend that you commission an independent consultant to prepare a report on what is wrong & what will be required to correct this.
I understand you want to find out yourself but with all due respect it is very complicated with all the component bits & how they will work or not together.

Just to answer a couple of your questions from earlier
1. You would need min of 35mm to shift 60kW @ Delta T 20deg C
2. The residual head pressure of the boiler pump in a 30kW boiler is less than 2 Metres this is not enough to overcome the resistance of the system fittings & pipework, hence why you don't have circulation. (you think it is bad now with outside temp of 15deg C just wait till the winter)

Please, I have seen enough of these Builders Plumber Jobs, get a pro in as soon as possible & you may want to sever your links with the installing plumber, I am sure his hart is in the right place but he is out of his depth on this one !!! More than likely he was almost forced to take it on by the builder or he wouldn't get any more work from them.

 

[CChris]

Appreciate the comments. Yes I do want to understand the issues myself but also appreciate that I'm not a plumber, so I'm in no way going to attempt to fix any issues myself or rely solely on answers from here to get things put right (although the advice is very much appreciated).

The under floor has been working. As has the heating. Both at different times and both in "manual" guise. I.e pumps plugged in and a single boiler on the wall etc.

I think the issues have arisen when it's come to sticking the second boiler on and connecting the lot up.

Yes there is still a decent chunk left to pay on the project of circa £30k plus another £4.5k retention, which I have zero intention of paying over until every single aspect has been demonstrated working.

For now the heating and hot water works in a fashion, so not the emergency it could be, but it will be inspected by another installer asap. Most likely the one I have had work on our office block.

You are almost certainly correct with the builder forcing the plumber to do it. This builder has very few contacts as he alienates almost every one he works with, and has been lucky not to wake with a horses head in his bed on this project if I'm honest. Had I not had some knowledge and another builder who has built rental properties for me in the past to call upon, he would have tried to slide some fantastic bodges past me. (Set a lintel too low, just cut the door frame down to suit.... as a minor example)

Really appreciate the input here guys, it is very helpful indeed. Hope I can return the favour somehow. If anyone is in the Chesterfield area and wants to have a look first hand and earn some beer tokens, feel free to drop me a message (apologies if this breaches any forum rules I am unaware of).

 

[stevetheplumber]

its badly undersized 22 isnt going to run even 15 radsyou are definitly going to need a low loss header and some bigger pumps

 

[CChris]

There are 19 rads on the 1st floor and 10 on the ground. Fed by a 22mm circuit to each, with the final connections to each rad being a mixture of 10mm or 15mm depending on their location either in the new or old part of the house (all pipe is new).


Are you suggesting I'm into having them lift the floor and replace all the 22mm run throughout the house?

 

[ShaunCorbs]

There are 19 rads on the 1st floor and 10 on the ground. Fed by a 22mm circuit to each, with the final connections to each rad being a mixture of 10mm or 15mm depending on their location either in the new or old part of the house (all pipe is new).


Are you suggesting I'm into having them lift the floor and replace all the 22mm run throughout the house?

maybe depends on how long the runs are/ how hes piped them

 

[CChris]

maybe depends on how long the runs are/ how hes piped them

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.

I guess all I can do as a basic test is to pop the tops off the trv's on all installed rads (20 out of the 29) and see if I can get them all belting hot in a not unreasonable length of time. If it can do that on one boiler then I'll probably be safe.

Worth adding that it is very unlikely I'll ever want them all on at the same time. Hence the evohome installation. It's more likely that only half the home would be heated at any point in time.

Still, I "should" be able to have them all belting hot at the same time.if I wanted, so it's no excuse for an undersized system if that turns out to be the case.

 

[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