Flow rate in central heating system

[Agile]

What was the boiler model the OP stated?

Which model has DM assumed is fitted?

( Are they the same ? )

Tony

 

[Biggles..]

38hxi same as 437give or take

 

[Biggles..]

Double post

 

[D_Hailsham]

Six pages on and I still don't know if this boiler has an internal pump !

You should do! The boiler is a Glowworm Ultracom 38hxi (page 1). A quick look at the MIs will show you that this boiler does not have an internal pump.

Keep up, your lagging behind.

Its not correct to run the system with TRVs on every radiator and just rely on the boiler to cycle. There should be a room stat to actually turn it off.

I agree. This needs to be dealt with urgently.

If there are TRVs on every rad then the system should have an ( auto ) bypass.

Again, I agree. It's in the MIs.

 

[edb49]

If there are TRVs on every rad then the system should have an ( auto ) bypass.

Again, I agree. It's in the MIs.

I'm 99% sure I've got one of these. There are three Ts with zone valves off from the flow side upstairs. There's a fourth T with a white hand-adjustable thing on made by Myson. It's about 1.5cm diameter.

 

[edb49]

as above from lcgs I recommend you call out an engineer familiar with these boilers but first try these settings

d0=30
d1=10
d71=75

the password for level 2 access is 35. I would say the primaries must be at least 28mm upto the controls (motorised valves) and you will need the pump lcgs quoted. The pump must be on it's highest setting.
The undefloor heating should be timed for at least 16hrs a day in the winter too.

d1 - I can't change this as there is no control cable for pump overrun.=-Well, I could change it but it wouldn't help much.

There is no d71 in the manual...

 

[Agile]

Earlier on you measured the boiler flow pipe as 26 mm external.

That really sounds closer to 22 mm than 28mm but its vitally important that the pipes are correctly sized if you want to get 38 kW out of your boiler.

However, as you say the problem occurs on just any ONE of your three circuits then there is a serious ( flow ) problem which is more serious than just a 22 mm flow pipe.

Have you checked the pump impeller and valves yet?

You said you think you have an auto bypass valve, what setting is that on?

Can you take and post some photos of the connections, motor valves etc?

Tony

 

[Biggles..]

Guys your missing the point.

This is a boiler swap,previous boiler and heating system worked adequately well.new boiler has S53

old boiler obviously had lower resistance than the new one,lower head of old boiler was enough for the pump.new head is too much.

Heating was fine,boiler swap induces problem.

Agile I'd your so sure normally you'd have quoted £84 pound fee by now.

If your honestly were closer I'd have alook gratis.

D71 2nd level diagnostics.

 

[Biggles..]

dam phone double post

 

[Biggles..]

Humour me for just one minute.

Old boiler,30+kw likely to be floor stood,cast heat ex low resistence with inch or inch quarter tappings

new boiler,38kw the size of a shoe box,22mm tappings and narrow waterway exchanger.

You can't surely believe that the added resistence of the new boiler,probably about 30KPa isn't the cause.

 

[Agile]

d1 - I can't change this as there is no control cable for pump overrun.=-Well, I could change it but it wouldn't help much.

There is no d71 in the manual...

Thats from some time ago!

I would interpret this as meaning that the pump is not controlled by the boiler!

This installation seems to get odder and odder ( as in not correct! ).

Tony

 

[Deleted member 105431]

the pump must be wired into the boiler, check the m.i's. Your system cannot absorb 38kw of heat into the system quick enough hence the s.53 so you must downrate it until the s.53 stops as a tempoary measure then rectify the sytem design/installation faults (undersized pipework, undersized pump, autobypass, balancing, poss dirt/sludge issue, poss blockage/restriction etc etc).

Call a professional in familiar with GW boilers ffs!

d71 is max flow temp and as you now say (I haven't read all 7 PAGES! ) that the pump isn't wired into boiler I wouldn't run it too hot (65 deg c max) as you may damage/scale up the heat exchanger.

 

[roguetrader]

alot of knowledgeable guys have thrown there thoughts in on this but its utterly useless if the OP isnt going to give the complete picture or answer guys questions. as DM said above you need to find a competant GW specialist in your area, try GW themselves. anyone half competant would know these have to have the pump wired directly from the boiler. it seems the system is beyond an easy fix and needs some proper attention.

 

[Agile]

Very well said to the last two posts!

I am keeping dead quiet now that he is apparently in Maidenhead where I have done a few boiler repairs ( but to Lee at £94 rather than £84 )

These little gems of mis-installation creep out slowly one by one and are difficult to follow hidden within 100 postings on the topic.

I am waiting with baited breath to hear if the pump impeller is blocked or not..... ( Lets see who is hooked by that! Hailsham? )

Tony

 

[Biggles..]

alot of knowledgeable guys have thrown there thoughts in on this but its utterly useless if the OP isnt going to give the complete picture or answer guys questions. as DM said above you need to find a competant GW specialist in your area, try GW themselves. anyone half competant would know these have to have the pump wired directly from the boiler. it seems the system is beyond an easy fix and needs some proper attention.

seriously why does it have to be wired direct,other than for pump over.As its fixed speed pump boiler cant modulate pump speed.

You could ignore the pump terminal and use a relay(SL make,SL break) and pipestat to acheive pump over run.

£94 for Tony to have a look might actually be a worthwhile spend.