Why is my heating so poor?

[slimwallet]

Gents,
Thank you all for taking an interest. I'll try and answer all the questions in turn:

doggit: I have raised the issue with another staff member of the installers but in the short time they attend the system is working albeit only slowly heating up the house. It seems to be a problem no one wants to own! Thanks for the instructions on use of menu's

Jackthom: Pump set to max flow. The E setting? "constant head "

AGAS: Have now checked D.00 setting and it is set at 30. The "Slimwallet" handle is a response to many years ago asking a simple query about an AV system on an AV forum and someone kindly spec ing a system for about £14.5K as the minumum acceptable for a decent sound and picture!

Muggles: NOt a huge house by anymeans. I don't know the old boiler rating but it could certainly pump out the heat. Rads could get very hot quite quickly. System size 13 rads with 11 in use as two bedrooms out of use. Right hand pipe out of boiler is much hotter than the left hand. Flushing was with external machine with separate pump. I didn't monitor rad temperatutre whilst it was running.

Here are some temp results from today from the boiler menu system:

6.30 a.m. System on Hall thermostat set to 21degC Boiler Outlet Temp set to 82DegC


Inlet d41 Flow d40

6.48 a.m. 51degC
7.06 a.m 32 degC 60degC
7.14 a.m. 34 61
7.25a.m 37 63
7.41a.m. 39 65
8.09 a.m. 41 67
8.40 a.m. 42 69
10.08 a.m. 41 67 (Hall temp now 18degC Lounge 18degC )
13.53 p.m. 42 69 (Hall temp now 19 degC Lounge 19degC )

The system has been on continuously. So after 7 hours still not up to temp.

I do keep thinking that flow must be an issue! BTW the house has been extended twice to my knowledge so I assume the pipe runs are quite tortuous.

Any more thoughts would be appreciated.

 

[muggles]

Sounds like your boiler is oversized for your house in that case. Not the whole problem in your case but certainly not going to help and not very efficient. A boiler half the size would probably have been enough. Anyway, to the main issue...looking at your d40/d41 temps, the flow is indeed approaching 30°C higher than the return, and that will cause your boiler fire in its protection mode, and possibly cycle on and off (is it firing continuously or going on and off if you watch it for a while?), to try to rectify this. It does sound like you have a circulation issue rather than purely a boiler power issue though. Is the pump turned up to max? Have you checked in your loft to see whether the F&E tank is getting hot (it should be cold)? Are your pump valves definitely fully open? Can you post a pic of where your F&E feed connects into the heating system?

 

[empty-seat]

Your installer has caused your problem by setting d.00 to 30 (instead of leaving it at Auto). This has severely restricted your boiler's ability to automatically modulate.

Change it to around 20 to see if that helps. If it does, pull up a boiler sizing calculator to work out the correct sizing for your property.

 

[D_Hailsham]

A rule of thumb is to assume 1.5kW average per rad. So with 13 rads that's 19.5kW, which is close enough to e-s suggested 20kW.

However I do wonder if 1.5kW is on the high side. I have 13 rads (ranging from 480W to 2kW) which total 12.9kW. I know this will be house-specific, so my house may be atypical. So it might be a good idea to wind d0 down to 15kw and see what effect it has.

Incidentally, such a large differential at the boiler should be really noticable when you touch the flow and return pipes. Is the same difference also found when you touch the flow and return at each rad (remove TRV head before checking so the rad gets maximum flow)?

 

[slimwallet]

Muggles: Pump has always been turned to max.
Have been in loft and F&E tank completely cold
Pump Valves fully open
Picture as requested

For D_Hailsham: Temp difference is very noticeable at most of the rads. I haven't checked every last one though.

For empty-seat: I will try turning down power tommorrow, thanks

 

[Steelmasons]

Install a 25/80 circulator or install another 15/60 in series with existing.
The Gloworm heat exchanger has a much higher resistance than the existing boiler..
Cylinder primary return should be fitted with a valve in order to reduce any short circuit while both heating and HW are calling.
Check/adjust ABV..

 

[muggles]

Looks like a sensible configuration, although that pump head should be horizontal rather than sticking upwards, as having it facing where it is now will considerably shorten its life expectancy

 

[snb]

Change. D 0. From 30 to 18
Change D 1 from 5 to 2
Change D2. From 20 to 3

This will stop the boiler going into anti cycling as much and keep,the boiler running longer.

It appears that you have a flow restriction or undersized pipework. The above alterations will get the boiler to put more heat into the system without it keep ramping down or going into waiting periods.

Before doing the above put the boiler in max mode to see if overriding causes the rads to get hotter. This only lasts 20 mins but will prove if it is a case of undersized pipework along with a boiler too powerful for your requirements.

 

[DP]

OP, try runnng CH with HW off at the programmer

 

[slimwallet]

snb: I don't understand "max mode" or how to put it into that mode. I will try the other settings later.
For the moment D.0 is now set to 15
I have noted when boiler first cuts in (at 6.30 a.m.) it is noisier with a bit of a roar. After about two minutes it is much quieter and carries on like that albeit heating very slowly. On the state listing the noisier period is S4 (burner on) and when it switches to quieter mode it is showing S3 (ignition?)

 

[DP]

Slim, suggest you check what I posted. It is not for the first time have been to properties where almost all the heat goes to cylinder resulting in similar situation to yours.

 

[Agile]

Or to more easily check what DP is wondering about, just turn off the programmer hot water while monitoring the heating warm up.

There can also be another cause and that is the cylinder stat could be set too high so I never reaches the set temperature at all but still produces a drain on the heat output from the boiler. But I don't think that is the problem in your case.

Tony

 

[Agile]

Your house is likely to have a heat loss of only 12 - 14 kW based on your description.

So who chose a 30 kW boiler?

Tony

 

[HERTS P&D]

Have your hot water come on 30 minutes before the heating.

Andy

 

[Roger928]

Looks like danfoss 2 port valves. The micro switches fail in those for a past time.