It's that time of year when one's thoughts turn to the smoothe running of ones CH system (sad isn't it!)
Before I go into all the details I'd just like to get some expert opinion on the suitability of the the UPS 15-50 in my system.
The pump has been running for years on the medium setting, but I've always been concious that the system didn't seem to be running right.
The radiators were not piping hot to the touch, the house didn't feel warm all over, and the boiler does a lot of 1-2 minute cycling.
Turning to this group again over the last week or so for some tips, I've treated myself to an IR themometer to do some proper investigation.
As I say at the moment I won't go into all the figures, but the info seemed to sugest that the pump needed to be on maximum. I've been running it like that for a few days and things do seem to have improved regards balance of heat even running all the LSV's open until I'm sure what the state of play is.
My main concernes at the moment are I never see anywhere near 80 degrees C at the input to the radiators, the boilier is cutting out when the ouput has reached this temp. The max input to closesest rad to pump is around 70 and the lowest is around 65. And the Boiler is still short cycling.
So before I try and rectify anything balancing like crazy I want to know if the UPS 15-50 is powerful enough or not.
I don't know this pump, what head rating is it? I had similar situation for many years inc boiler kettling at times. When I changed the pump for the second time I went for a beefer pump with a
6m head. It runs a lot quieter on its medium setting and the system works much better too.
If this is microbore then a more powerful pumps appears the answer. Unless there is sludge in the system blocking pipes. Did it ever work properly? The boiler appears to be getting up to temp, so that appears to be working fine.
Microbore requires generally a larger pump than a 15-50. A 15-50 generally was not used on a house that large. Go for the next size up. and then do your tests.
The annoying thing is I'm sure I fitted this myself soon after moving to the house because the existing (non Grundfos) pump was very noisy. I no longer have it to check what the rating was, but I'll pop round a neighbours and see what theirs is.
Is a 15-60 going to be sufficient of an improvement?
I did flush out and Fernox the system a couple of years ago, but I don't know how good a job that would have been rated as.
This means hat either the boiler thermostat has a problem or that the heat is not being delivered from it rapidly enough. The latter can be because of poor circulation or because the boiler is oversized/burn rate set too high for the installation or both.
This does all point to poor circulation as at least one of the factors.
Is the system using microbore pipe (e.g. 8mm)? This may present a higher system resistance and require a higher pump head.
Have you checked for sludging?
If you have TRVs especially, a better pump option could well be the Grundfos Alpha. There is a 15-60 model of this which has a 6m max head as opposed to the 5m of the UPS 15-50. It also adapts its output to match the resistance requirements.
However, before doing a pump swap, I would check for why the circulation is poor.
The Boiler is a GlowWorm FuelSaver 55F with a rated output between 35k & 55k Btu/h. Its anyones guess as to what it has been set to. The manual talks about putting a suppied self adhesive label by the data plate to record setting but guess what I can't see one :-)
Yes it is 8mm Microbore (I put it in the Subject line but should have also included it in the body text too for clarity sorry)
What is the best way of doing this (i.e. least messy )
Cliff, I had exactly the same problems with a 15mm system. The temperature of the water at the rad inputs is a function of the boiler thermostat setting as well as the flow rate. I strongly recommend balancing the system per recent threads here and the faq.
Initially I cranked my pump up to max to achieve the correct drop across the boiler, but once the system was balanced, reset it to the mid position. I then replaced it with a 15-60 Alpha + pump simply because this new unit has an electronically controlled pressure output to take into account thermostat valve operation around the house.
I was surprised at how much effect on temperature stability and boiler cycling the balancing had.
I'd second that - use a 6m head Grundfos Alpha. It is rather more expensive but offers a continuously variable setting to match most applications plus three fixed settings for special cases. And it's sooooooo quiet.
I want to balance my CH system at some time over the next few months. What is an IR thermometer, where did you get it and how much did it cost? I've been looking out for balancing thermometers but not found any. I notice the FAQ on the subject was written by someone who used thermometers he bought from Maplin.
It doesn't matter greatly - this is a 10-16kW range and I would be surprised if it is oversized for a house of this size. If you had said twice this figure then I would have suggested looking further.
Sorry, I missed it in the subject line.
Before doing this, another thing to check is the motorised valve(s). It could be that this is stuck or blocked. Try taking off the head and turning the cam manually. You can also try operating the manual lever on the valve. Sometimes the gearing mechanism in the head fails. Any problems in this area and the general flow to the CH can be poor. The fix is to replace the valve, which is an easy enough job..
Next, I would go round and open all of the lockshield valves fully and check behaviour again. It could be that this is problem. If it isn't, and there is a sludge problem then you will need to open them all anyway.
To check for sludging and to resolve:
Pick a radiator where it is easy to get some old towels underneath plus some polythene. A downstairs relatively smaller one is probably better since fine sludge particles are likely to have collected more so in lower radiators. You then need some containers to go underneath each end of the radiator. I bought cat litter trays from the supermarket. They're cheap, the right height and will take a fair amount of water. You do need to take some care because sludgy water is an effective dye.
With the heating off, turn off both valves on said radiator and carefully undo one of the union nuts to let the water drain into one tray, then undo the other. If you do it slowly, you can control the flow easily. Undo the vent as well. Once the water has stopped trickling out, lift and tip it to one end and see if sludge comes out. If there is a fair amount, then you will have pretty dirty water and sludge before this anyway.
Fasten small plastic bags over the radiator tails and take the radiator outside. Give it a flush through with a mains hose or pressure washer. With the radiator still off the wall, carefully open each radiator valve and check that you are getting a respectable flow of water. There may well be further sludge in the pipes if there are long horizontal runs, but there should be enough head of water from the feed tank in the roof (this is open vented system, yes?) to flush out the pipes.
It will be reasonably clear if sludge has been the problem by this time. If it is, then you need to repeat the exercise at each radiator. Finally, give the system a good flush through with clean water from the roof tank.
By this time, either because you opened the lockshields, resolved a problem with the motorised valve(s) or with sludge, you should be able to get reasonable flow on the pump mid and high settings. Before my heating refurbishment, I had a 15-50 pump on an 8mm system and it was fine.
If you have done the cleaning exercise, I would then put in some flushing/cleaning agent and run the system hot for a week. Then drain and flush again.
Once you've done all of this, then an Alpha pump may help further. If I had still got the old system I would have replaced my pump with one. As it was, I have one in my new boiler which is controlled by it to match the heat output. However, I do have an Alpha on my separate workshop circuit and that works well. The run from the house to the workshop is quite long and the pipe resistance higher than for a circuit purely within the house, so the extra head is a help.
However, before splashing out for one of these, I would check for the more obvious things that are limiting flow first.
OK this might be an interesting one,could be on to something. I've removed the operating head off the only motorised value in the past now when it has been making a bit of a noise to find the valve below stuck. With some gentle persuasion with pliers I've managed to free the valve. How much should this turn? It only moves probably less than 1/8 of a turn. What is the correct proceedure for putting the head back on? Does the motor/spring need to be under tension? Is there a right and wrong way to turn the head when mating up to the spindle?
It does not appear possible to just run the CH with the head removed as the motor continues to turn and the cams cut the pump off on each revolution and then come back on again, thinking out loud perhaps with the HW switch on it won't do this.
As it is now the manual overide lever doesn't go under tension in either direction.
Thanks for responding so quickly. They look very nice. This is gping to sound dozy but, do you need two, or do you just 'scan' across the ends of the rad to get the two flow/return readings?
It's the "taking it outside" bit that I found so difficult when I followed your advice for my system :-) Not so much a DIY job as a DIY and have a friend handy with big biceps!
Hmm.. That's concerning. It can sometimes happen after the summer if the heating has not been on. It shouldn't otherwise. You can avoid the summer issue by turning the heating on briefly evey week or so.
I haven't looked at one for a few months, but I think it should move a bit more than that. There are two main designs. One type has a kind of cylindrical rotating paddle inside and is generally able to rotate continuously. The other, which seems to be more common, has a roughly spherical rubber component inside which is mounted eccentrically. As this rotates it opens and closes against one port or the other with a 3way valve and just against the port in a two way valve. These tend to have restricted travel.
There is basically a motor and gear train in the head and a big spring. With power off the spring moves the actuator position to one end of its travel. With power on, the motor runs the actuator to the other end and then stalls (it's designed to do this). Basically with the power off, you manually move the cam on the valve base so that it will line up with the head as you locate it into place. It should only go one way.
It sounds like the spring might have gone or possibly part of the gear train has stripped because the valve base was stuck.
Normally, with the power off you should be able to slide the lever and operate the valve, then latch the lever at the far end of the travel in a notch in the case of the head. If you release it then it should return under spring tension.
You probably would be able to fool the system by having the valve head off of the base and creating a hot water demand, as you say, Then operate the cam on the valve base to the CH position.
If it then works OK, I think that pretty much you will have diagnosed a faulty head. They are easy to change, but note the wiring connections.
Since you have been having valve sticking problems, I would replace the valve base as well. You can buy the complete thing pretty cheaply.
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