Some heating circuits not working well - what to do..?

[reb78]

before you fit the new pump to the manifold how did your system work before

note minibore pipe means faster flow of water through to the rad

what sort of issues did you have

There was a manifold under the floor that was just rigged (badly) into the old system that supplied what the JG manifold now does. We removed the old one to add this pump in the hope that a pumped manifold would improve things. The old system was worse than this and the most problematic rad may as well have been off most of the time.

Re the microbore - yes, that was my understanding too.

issues - as above - worse than now with the rest of the house working fine. My friend/plumber thought the pumped manifold should fix it. I will ask him to come take another look but was curious what folk on here thought.

 

[reb78]

Did your replace the flow valves with plugs as suggested in the other thread. I suspect with the low flow rates you are getting preferential flow as water will take the easiest route. If all circuits work individually you will need to balance as suggested.

Yes, replaced the flow valves on the three troublesome rads. I left them on on the two that were working fine. I have attempted to balance this manifold but will try again. I just wondered if it was more fundamental as any attempt at balancing seemed to make little difference. My IR camera is on charge...

 

[Mikes]

That's probably your problem there. The two pumps will be trying to fight each other. The pipework needs changing such that they are both connected to a low-loss header (basically an oversized piece of pipe) . It's also preferable to have the pumps either pumping upward (not easy in your layout) or in the horizontal. both aid efficient air removal.

 

[reb78]

Post up a simple sketch of how the two pumps are connected to the heat store please so we can get the full picture of the system.

Added a pic above as am aware my descriptions arent the best!. I think that gives what you need.

 

[Mikes]

Forgot to add, what is the third pump (red one) doing? Is this from the heat source?

 

[reb78]

That's probably your problem there. The two pumps will be trying to fight each other. The pipework needs changing such that they are both connected to a low-loss header (basically an oversized piece of pipe) . It's also preferable to have the pumps either pumping upward (not easy in your layout) or in the horizontal. both aid efficient air removal.

So almost a flow manifold in itself, that the pumps take a feed from?

Haha - yes, the pumps are the opposite of upright or horizontal in this setup!

 

[reb78]

Forgot to add, what is the third pump (red one) doing? Is this from the heat source?

Sorry - should have explained that one - this is from the oil boiler. In the winter we dont need it as the Rayburn is sufficient to heat the store, so it only gets used for 20 mins a day to do hot water in the summer months.

 

[addjunkie]

Sorry - should have explained that one - this is from the oil boiler. In the winter we dont need it as the Rayburn is sufficient to heat the store, so it only gets used for 20 mins a day to do hot water in the summer months.

If you moved to a 1 room open plan flat, you wouldn't have all this complicated heating going on, life would be far simpler. Note…” Ive disconnected my back boiler log burner from our heat store and fitted a normal log burner, and finally got my holiday cottage heating all balanced again at sensible temperatures since we had guest fiddlers so have now screwed door shut so no one can fiddle now. I hate fiddling with heating.”

 

[DanZac]

To me it still comes back to balancing (although I fully agree with the other points ref pump fitment etc). The first thing you need to do is get the same flow through each pump (balancing).

Personally I'd shut off all the rads except the closest one on each circuit (fully open that one) and get the return temp on each pump running at the same temp.

You'll need to slow the best fed one down (or limit the flow through it via the isolating valves) Once you've got the flow through each pump equal you can start adding the other rads back in and go from there.

As others have said, the pump set up is far from ideal, but if you can get the pumps balanced that should give you a starting point for sorting out the radiators and wil prove if the system will even work.

If you can't get the pumps balanced then I don't think you've got much chance of getting heat to all your radiators. (ps I'm not a plumber so feel free to ignore my ideas)

 

[gaz1]

wow for this pic



bleed valve should be tee'ed off at the elbow point so can trap air at the tank

treat the system as seperate systems so just unplug house pump and equalise that system first try to see what happens with just those 4 rads on with the pump this is goign to take a while to get right

this depends on your pump speeds

set pump too 2 or 3 on that circuit once tested and they are all running fine then its the house circuit

set the pump to 1 shut down the other circuit by unplugging that pump then equalise that circuit

this adjusts the flow of water to equalise between both systems at different flow rates run the system and check the rads for hot heat on all of them

let the system cool down, run as a first run and check what rads get hot first its either going to be the house rads or the manifolds rads

they should all equal out on there heat between the rads

if you want more speed adjust the speed of pump by switching to 2 on house and the other pump too 3

 

[voipio]

This radiator balancing malarkey in domestic systems has never sat comfortably in my mind. I'm not saying that it doesn't work at the time it's done, because it does work, and is necessary if there aren't any TRVs on the radiators themselves. But, in the longer term, the flow restriction can be a place where blockages can occur. It only takes a couple of lumps of magnetite, or some other contaminant, larger than the size of the restriction, to lodge at that point and start the blocking process. I prefer systems where there are TRVs on every radiator, except one, lockshield valves more or less open and, once a room comes up to temperature, the TRV reduces the flow to the rad, allowing a greater share of the flow to reach the remaining radiators on the circuit. Yes, the room(s) with the initially flow-starved radiators take a bit longer to reap the benefits, but they get there, usually within half an hour, or so of the heating coming on.

A thermal camera can be very useful for visualising heat flows in radiators.

Out of interest, does the system gurgle much when it's on?

 

[bricol]

TRVs have got nothing to do with balancing a system. You still need to do it, or the system will never work properly.

I couldn’t ever get mine to work as I couldn’t get a reliable temp reading from each radiator supply and return pipe.

Black tape stuck to each pipe, IR temp gun from Aldi, held the same distance from each one and voila – heat from all radiators.

If you don’t guide the flow to where it’s needed, it simply takes the path of least resistance, whatever fluid system you are working with – domestic heating system using hot water is no different.

As for crap in the system – fit a filter, use inhibitor. My filter pulled an enormous amount of crap out of the system in the first few weeks of having fitted it, then pretty much nothing from then on.

I’m redesigning the cooling system on a 30 ton, every expensive, machine, basically an 8 colour high speed printing press, at the moment where the previous designer had some very funny ideas – I suspect he’d never worked with pipework, pipe fitting, or pumped water flow before. Also seems to have accepted the challenge to use as many of the expensive fittings in a Parker catalogue as possible . . .

 

[Mark 5]

This radiator balancing malarkey in domestic systems has never sat comfortably in my mind. I'm not saying that it doesn't work at the time it's done, because it does work, and is necessary if there aren't any TRVs on the radiators themselves.

TRVs and balancing a CH system have nothing to do with each other.

 

[Mark 5]

Sorry - should have explained that one - this is from the oil boiler. In the winter we dont need it as the Rayburn is sufficient to heat the store, so it only gets used for 20 mins a day to do hot water in the summer months.

The way the pumps are set up, not great, be that as it may, like others I do think your CH system needs to be correctly balanced.

Not helping matters is the mixture of pipe sizes.

How many rads total in the system?

 

[reb78]

The way the pumps are set up, not great, be that as it may, like others I do think your CH system needs to be correctly balanced.

Not helping matters is the mixture of pipe sizes.

How many rads total in the system?

16 rads in total.

It's hard. I'd redo the whole lot as the previous owners clearly added bits here and there as they felt like it, but tearing the house apart to do that isn't an option at the moment. Everything other than the rads off of this manifold works OK.

 

[reb78]

So, with only the pump to the manifold connected and all rads on that manifold turned off other than the furthest most troublesome one, the furthest rad still took an age to get warm - basically ALL the hot water was being sent to it. I mean its been on maybe 15 mins and the return at the manifold is barely warm, the radiator was starting to get warm. Pretty sure there isn't air in it as have flushed it with a hose to clear that.

In my head, it suggests an issue with the pipework? Could be the pump perhaps but it seems to draw hot through to the manifold. But if the pipework is at fault, why, if i connect the pipework up to a hose on the cold tap (isolate the manifold from the system and stick a hoselock on the end of the flow and return manifolds), do i get good fast flow and not a lot of crud?

 

[Mark 5]

16 rads in total.

It's hard. I'd redo the whole lot as the previous owners clearly added bits here and there as they felt like it, but tearing the house apart to do that isn't an option at the moment. Everything other than the rads off of this manifold works OK.

16 rads, its a lot, out of interest what is the BTU output of your boiler?

The fact you can get the troublesome rads to heat when you close things down does suggest a balancing issue.

You will be aware of this yourself but it won't be the first time I've all most had to close rads down to balance a system.

 

[reb78]

16 rads, its a lot, out of interest what is the BTU output of your boiler?

The fact you can get the troublesome rads to heat when you close things down does suggest a balancing issue.

You will be aware of this yourself but it won't be the first time I've all most had to close rads down to balance a system.

Its more the Rayburn than the boiler thats relevant i think - which i think is 50000 BTU - that sounds undersized but it runs constantly and the way we have the system setup it trickles round the house 24 hours a day - i.e. when the heat store gets to 55C half way down. I wonder if this is part of the problem - i.e. we dont really run it on the boiler heavily a couple of times a day and get it all really hot.

The house isnt that cold, but some rooms with the rads that work less well will get chilly when there is ice and colder weather.

I need to balance it properly from reading this thread - but what makes me wonder if that will have an effect is the post above where if i literally get the pump to run through the most troublesome rad only - i.e. no others receiving pumped water, it still takes forever to get warm. Trying to figure out the order of heat up of the 12 rads on the main system is nigh on impossible too!!

(I think the oil boiler is 90,000-110,000 BTU depending on its setup BTW but at worse, that needs to run this house and the 2 bed annexe)

 

[DanZac]

I need to balance it properly from reading this thread - but what makes me wonder if that will have an effect is the post above where if i literally get the pump to run through the most troublesome rad only - i.e. no others receiving pumped water, it still takes forever to get warm. Trying to figure out the order of heat up of the 12 rads on the main system is nigh on impossible too!!

When you shut everything down and just run that one rad does the return to the boiler get hot or nothing?

If the pipework gets hot but not the rad, being the furthest away it may have a bypass fitted to allow flow even if all the radiators are off to prevent overpressure/ stalling the pump, which is incorrectly adjusted and just allowing flow straight back to return as the easiest path.

(You normally have at least one radiator that's always on to do the same, but I have seen systems set up with a bypass set up instead).

 

[voipio]

I need to balance it properly from reading this thread - but what makes me wonder if that will have an effect is the post above where if i literally get the pump to run through the most troublesome rad only - i.e. no others receiving pumped water, it still takes forever to get warm. Trying to figure out the order of heat up of the 12 rads on the main system is nigh on impossible too!!

This does suggest a blockage of some sort in that particular radiator, or its pipework, though you say you've ruled that out. Presumably there's not any underfloor heating, or other type of "heat sink" on that radiator circuit, since you said previously that various bits have been added by the previous owner, over the years.