System design advice please!

[Andygasman2010]

A bit of advice needed on this, got a customer that's moved into a house with a cowboy installation!

It's a large-ish house with 30 rads over three floors. It's a Glowworm 38HXI on an S-plan, grundfos 15/60 and a 250L unvented cylinder all installed in the cellar. All on plastic 22/15mm (barriered)

Problem i've got is the top floor doesn't heat at all and when the boiler comes on it cycles high/low every few seconds (when I open the bypass it stops cycling and runs ok) I think the pump/pipework is way undersized and can't get rid of the 38KW. Trouble is, I can only touch the plan/boiler pipework as the rest of it is tiled under floors etc.

I was thinking of upgrading the visible pipework and pump and maybe installing some kind of LLH or buffer to help the boiler stop cycling. Keep the 15/60 for the boiler and use a 25/55 for the system.

Would this set-up mean too narrower temp-diff accross the heat ex meaning it wouldn't condense?

Or am I barking up the wrong tree completely! Just trying to avoid telling the guy his expensive floors need to come up!

Thanks

 

[spraggo]

With that size system the poor old grunfoss 15/60 seems rather inadequate.

spraggo

 

[mehran]

seen a local plumber to me at the merchants the other day picking up a massive wilo pump a a cost of £400 notes

it was a 30 rad system that was not heating correctly...new build house as well.

think the pump he got was a wilo stratos

 

[Agile]

Better in the CC

 

[Biggles..]

25/55 won't help you much either.Boiler at full rate has a resistance of about 35Kpa,3storey property I'd estimate the index to be inexcessive of 30KPa.
I would have thought you should be looking at 25-80(28mm primaries).

38kw, would deffinately need 28mm primaries possible even 35's

If it's not currently sealed system fit a robokit that'll help improve things a little.

If you fit the header all your system Pump has to fo is overcome the index circuit and has no need to worry about the boiler resistance.either way it's repipe,alter configuration and supply a new pump.

Wilo stratos,good modulating pumps,cheaper from flowmech at Leicester (main wilo distributor) than any merchant you buy from regardless of your terms.

 

[Andygasman2010]

Better in the CC

Thanks, i'll copy/paste it over.

 

[spraggo]

Better in the CC

Hi Agile,
With the greatest of respect, why did you suggest sending this topic to CC when it has nothing to do with gas.

Regards

spraggo

 

[seco services]

why did you suggest sending this topic to CC when it has nothing to do with gas.
spraggo

if it was asked by a diy'er then it would stay here.

 

[spraggo]

if it was asked by a diy'er then it would stay here.

How interesting, put it this way, I don`t want to bore you with my life story but I can remember way back in 1968 when I was promoted to a "Gas Installer" by the local gas board. In 1971 I automatically became a CORGI installer with the reg No SW.0427. In 1989 CORGI became compulsory and I still have all the reg certificates from then until 2007 when I retired. I am relatively new to this forum and as you will note, my CC registration application is still pending since I applied over to months ago. I would like to add that I was also a shell and BP oil installer leading on to being OFTEC. I was also a member of IOPHE and HVCA.
So I don`t understand why I and many others, with similar qualifications,
have to belong to the CC to express thei views on plumbing and heating that does not concern gas. ( Hope the Diy admin reads this).

spraggo

 

[seco services]

cause half the country wants to eat/sleep rules/regs.
shame half the country never follow them then.

 

[spraggo]

cause half the country wants to eat/sleep rules/regs.
shame half the country never follow them then.

It appears that RGI`s are classed as (half the country then).

 

[seco services]

It appears that RGI`s are classed as (half the country then).

don't matter what it is or who it is the countrys got an obsession with rules/regs.

 

[spraggo]

[quote="seco services";p="1810334don't matter what it is or who it is the countrys got an obsession with rules/regs.[/quote]




With you being a RGI i see exactly what you mean, say no more.

spraggo

 

[Norcon]

don't matter what it is or who it is the countrys got an obsession with rules/regs

The english seem to have an obsession but I guess when you're living shoulder to shoulder with over 50 million crammed into a tiny space, regs are inevitible coupled with jobs worths who cite someone getting hurt or dying every once in a blue moon and another regulation or two will generate income for some unproductive pen pusher.
Is it any wonder the country is bankrupt?

 

[bengasman]

Is the system open vented by any chance?
I know most people here want to shoot me for saying so, but in my experience a HE boiler can easily do up to about 10 kw of output on 15 mm pipe.
I don't know the boiler specifically, but I would guess that it will ramp down to about 10 kW or less when needed. That means that even if the primaries were only 15 mm in stead of 22, it should not cycle.
You may need to upgrade some of the pipework to get the system going perfectly, but your immediate problem lies somewhere else.